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WACE ATAR Physics study materials
WACE ATAR Physics study resources

WACE ATAR Physics practice questions

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Question 1Science Inquiry Skills

A student measures the length of a metal rod five times and obtains values of 12.4 cm, 12.5 cm, 12.4 cm, 12.3 cm, and 12.4 cm. Which statement best describes the quality of these measurements?

  1. The measurements are both inaccurate and imprecise
  2. The measurements show a clear systematic error
  3. The measurements are precise but their accuracy cannot be judged without a known true value Correct answer.
  4. The measurements are accurate but imprecise

Explanation

Precision describes how closely repeated measurements agree with each other, and these values cluster tightly around 12.4 cm, so precision is high. Accuracy describes closeness to the true value, which requires an accepted reference value that the question does not provide. Therefore only the precision can be assessed from the data given.

Question 2Science Inquiry Skills

Which of the following is the most appropriate instrument for measuring the diameter of a thin wire to a precision of 0.01 mm?

  1. A micrometer screw gauge Correct answer.
  2. A measuring cylinder
  3. An electronic top-pan balance
  4. A metre rule

Explanation

A micrometer screw gauge typically has a resolution of 0.01 mm, making it suitable for measuring small diameters such as thin wire. A metre rule resolves only to about 1 mm, which is far too coarse. The other instruments measure volume or mass and cannot measure diameter directly.

Question 3Science Inquiry Skills

A student records the volume of a liquid as 25.0 mL using a measuring cylinder with 1 mL graduations. Which statement about this reading is correct?

  1. The uncertainty is about ±0.5 mL because the smallest division is 1 mL Correct answer.
  2. The uncertainty is ±5 mL because the cylinder is large
  3. The reading cannot be trusted because measuring cylinders are never used for volume
  4. The uncertainty is negligible because a decimal place was recorded

Explanation

When an analogue scale has graduations of 1 mL, the reading uncertainty is commonly taken as half the smallest division, that is about ±0.5 mL. Recording a decimal place does not reduce the instrument's inherent uncertainty. The uncertainty depends on the scale divisions, not on the overall size of the cylinder.

Question 4Science Inquiry Skills

A student measures the mass of a sample as 4.0 g using a balance with an uncertainty of ±0.1 g. Which expression correctly represents the percentage uncertainty in the mass?

  1. 4 percent
  2. 40 percent
  3. 0.1 percent
  4. 2.5 percent Correct answer.

Explanation

Percentage uncertainty equals the absolute uncertainty divided by the measured value, multiplied by 100. Here that is (0.1 ÷ 4.0) × 100, which equals 2.5 percent. This shows how relative uncertainty decreases as the measured value increases for a fixed absolute uncertainty.

Question 5Science Inquiry Skills

In an experiment, a student plots a graph of period squared against length for a simple pendulum. The graph is a straight line through the origin. What does the gradient of this graph represent?

  1. The mass of the pendulum bob
  2. The reciprocal of the acceleration due to gravity multiplied by four pi squared Correct answer.
  3. The square root of the length
  4. The acceleration due to gravity

Explanation

For a simple pendulum, the period squared equals four pi squared times length divided by gravitational acceleration. Rearranging gives period squared on the vertical axis against length on the horizontal axis with gradient equal to four pi squared divided by g. Hence the gradient is proportional to the reciprocal of g.

Question 6Science Inquiry Skills

Which of the following best describes a controlled variable in an experiment?

  1. A quantity that is always zero
  2. A quantity deliberately changed by the experimenter
  3. A quantity that is kept constant to ensure a fair test Correct answer.
  4. A quantity that is measured as the outcome of the experiment

Explanation

A controlled variable is held constant throughout an experiment so that it cannot influence the outcome and confound the result. The independent variable is the one deliberately changed, and the dependent variable is the one measured. Keeping other factors constant allows a fair test of the effect of the independent variable.

Question 7Science Inquiry Skills

A student repeats a measurement many times and calculates the mean. Which statement best explains why taking a mean reduces the effect of random error?

  1. The mean guarantees the result equals the true value
  2. The mean removes all systematic error from the data
  3. Random errors cancel partially because they scatter above and below the true value Correct answer.
  4. The mean increases the resolution of the instrument

Explanation

Random errors scatter in both directions about the true value, so averaging many readings allows positive and negative deviations to partially cancel. This reduces the uncertainty of the mean compared with a single reading. Systematic errors, however, shift all readings in the same direction and are not removed by averaging.

Question 8Science Inquiry Skills

Which of the following is an example of a systematic error?

  1. Small vibrations causing fluctuating readings
  2. Reading a scale slightly differently each time
  3. Fumbling and dropping a sample occasionally
  4. A balance that consistently reads 0.2 g too high for every sample Correct answer.

Explanation

A systematic error is a consistent bias that affects every measurement in the same way, such as a zero error in a balance. Because the offset is the same each time, averaging does not remove it. The other examples produce random variation rather than a consistent shift.

Question 9Science Inquiry Skills

A student calculates a derived quantity using the formula v = d/t, where d = 20.0 ± 0.2 m and t = 4.0 ± 0.1 s. What is the percentage uncertainty in the calculated speed?

  1. 4 percent
  2. 1 percent
  3. 2.5 percent
  4. 3.5 percent Correct answer.

Explanation

When quantities are divided, their percentage uncertainties add. The percentage uncertainty in d is (0.2 ÷ 20.0) × 100 = 1 percent, and in t is (0.1 ÷ 4.0) × 100 = 2.5 percent. Adding these gives 3.5 percent for the speed.

Question 10Science Inquiry Skills

Which of the following statements about the reliability of experimental data is correct?

  1. Reliability is improved by using a single precise measurement
  2. Reliability is the same as validity
  3. Reliability is improved by repeating measurements and obtaining consistent results Correct answer.
  4. Reliability depends only on the accuracy of the instrument

Explanation

Reliability refers to how consistently an experiment yields the same results on repetition. Taking multiple measurements and finding them consistent increases confidence in reliability. A single measurement, however precise, cannot demonstrate consistency.

Question 11Science Inquiry Skills

A student investigates how the extension of a spring depends on the applied force. Which variable should be plotted on the horizontal axis to produce a straight-line graph through the origin?

  1. The extension of the spring
  2. The mass of the spring
  3. The time of stretching
  4. The applied force Correct answer.

Explanation

The independent variable, the applied force, is conventionally placed on the horizontal axis. Hooke's law predicts extension proportional to force, giving a straight line through the origin. Plotting in this way allows the spring constant to be found from the gradient.

Question 12Science Inquiry Skills

Which of the following is the best example of a valid conclusion drawn from an experiment?

  1. The hypothesis is proven correct because one trial gave the expected result
  2. The hypothesis is supported because the trend in the data matches the prediction Correct answer.
  3. The hypothesis is false because the equipment was expensive
  4. The hypothesis is supported because the student expected it to be

Explanation

A valid conclusion is based on evidence from the data and states whether the results support the hypothesis. It should refer to observed trends rather than expectations or single trials. Scientific conclusions support or fail to support hypotheses rather than proving them absolutely.

Question 13Science Inquiry Skills

A student wishes to improve the validity of an experiment measuring the effect of temperature on the rate of a reaction. Which action best improves validity?

  1. Repeating each temperature trial three times
  2. Ensuring only temperature is varied while all other factors are held constant Correct answer.
  3. Recording results to more decimal places
  4. Using a more precise thermometer

Explanation

Validity depends on controlling all variables except the one being tested so that any change in the outcome can be attributed to that variable. Holding concentration, volume, and other factors constant ensures the experiment tests what it claims to test. Repeating trials and improving precision mainly affect reliability and uncertainty.

Question 14Science Inquiry Skills

A graph of voltage against current for a resistor gives a straight line through the origin. The gradient of the line is 12 V per A. What physical quantity does this gradient represent?

  1. The charge stored
  2. The power dissipated
  3. The capacitance
  4. The resistance of the resistor Correct answer.

Explanation

Ohm's law states that voltage equals current multiplied by resistance, so a graph of voltage against current has a gradient equal to resistance. A gradient of 12 V per A corresponds to a resistance of 12 ohms. Power, charge, and capacitance are not given by this gradient.

Question 15Science Inquiry Skills

Which of the following best describes the purpose of a control group in an experiment?

  1. To increase the number of measurements taken
  2. To provide a baseline against which the effect of the treatment can be compared Correct answer.
  3. To reduce the random error in the equipment
  4. To ensure the independent variable is changed

Explanation

A control group is not exposed to the treatment and provides a baseline for comparison. Comparing the treatment group with the control group allows the effect of the independent variable to be isolated. It does not itself increase sample size or reduce instrument error.

Question 16Science Inquiry Skills

A student measures the time for a ball to fall using a stopwatch and obtains 0.42 s. The reaction time of the student is about 0.2 s. Which statement best describes the effect of reaction time on this measurement?

  1. The reaction time is a systematic error that can be corrected by averaging
  2. The reaction time is a large fraction of the measured time, so the result is unreliable Correct answer.
  3. The reaction time improves the precision of the measurement
  4. The reaction time is negligible compared with the measured time

Explanation

A reaction time of about 0.2 s is nearly half of the measured 0.42 s, so human reaction contributes a very large uncertainty. This makes the stopwatch measurement unreliable for such a short interval. Averaging does not remove reaction-time error because it is not random in a simple way and is large relative to the value.

Question 17Science Inquiry Skills

Which of the following is the correct way to report a measurement with its absolute uncertainty?

  1. Mass = 5.234 g ± 0.123 g
  2. Mass = 5 g ± 0.001 g
  3. Mass = 5.234 g ± 0.1 g
  4. Mass = 5.2 g ± 0.1 g Correct answer.

Explanation

The uncertainty should be quoted to one significant figure, and the measured value should be given to the same decimal place as the uncertainty. Therefore 5.2 g ± 0.1 g follows the convention. Quoting extra decimal places in the value or uncertainty implies unjustified precision.

Question 18Science Inquiry Skills

A student measures the density of a metal by dividing its mass by its volume. The mass is known to ±2 percent and the volume to ±3 percent. What is the percentage uncertainty in the density?

  1. 2.5 percent
  2. 5 percent Correct answer.
  3. 1 percent
  4. 6 percent

Explanation

Density is calculated by dividing mass by volume, so the percentage uncertainties add. Adding 2 percent and 3 percent gives 5 percent. Multiplying the uncertainties or subtracting them would be incorrect for a division.

Question 19Science Inquiry Skills

Which of the following best explains why a hypothesis must be testable?

  1. So that it can be accepted by popular opinion
  2. So that predictions can be compared with experimental evidence Correct answer.
  3. So that it can be written in a complex way
  4. So that it can be proven true without any experiment

Explanation

A testable hypothesis generates predictions that can be checked against experimental evidence. This allows the hypothesis to be supported or refuted by data. A hypothesis that cannot be tested cannot be evaluated scientifically.

Question 20Science Inquiry Skills

A student obtains the following repeated values for a measurement: 8.1, 8.2, 8.0, 8.1, and 8.1 units. Which statement about the data is correct?

  1. The mean is 8.0 units and the results are inconsistent
  2. The mean is 8.5 units and the spread is large
  3. The mean is 8.1 units and the spread is small Correct answer.
  4. The mean is 8.1 units and the spread is large

Explanation

The sum of the five values is 40.5, so the mean is 8.1 units. The values lie between 8.0 and 8.2, indicating a small spread and therefore good precision. The consistency of the readings supports the reliability of the measurement.

Question 21Science Inquiry Skills

In an experiment, a student finds that doubling the independent variable doubles the dependent variable. Which relationship does this describe?

  1. A linear relationship through the origin Correct answer.
  2. An inverse-square relationship
  3. A quadratic relationship
  4. An exponential relationship

Explanation

If doubling the independent variable doubles the dependent variable, the dependent variable is directly proportional to the independent variable. This is a linear relationship that passes through the origin. Inverse, exponential, and quadratic relationships would produce different changes.

Question 22Science Inquiry Skills

Which of the following is the most appropriate way to reduce the effect of parallax error when reading a measuring cylinder?

  1. Reading the top of the meniscus
  2. Shaking the cylinder before reading
  3. Reading from a distance to see the whole scale
  4. Viewing the meniscus at eye level Correct answer.

Explanation

Parallax error occurs when the scale is viewed from an angle, so the apparent position of the meniscus is displaced. Viewing at eye level aligns the eye with the meniscus and the scale. The bottom of the meniscus should be read, and shaking would disturb the liquid level.

Question 23Science Inquiry Skills

A student plots a graph of the square of the period of a pendulum against its length. The graph is a straight line but does not pass through the origin. What is the most likely explanation?

  1. The gradient is exactly equal to g
  2. There is a systematic error or an unaccounted constant in the relationship Correct answer.
  3. Random errors have been eliminated
  4. The data are precise

Explanation

A straight line that misses the origin indicates either a systematic measurement error or an additional constant term not included in the simple model. The standard pendulum relationship predicts a line through the origin. Precision and the removal of random error would not shift the intercept.

Question 24Science Inquiry Skills

Which of the following best describes the role of a risk assessment in a physics investigation?

  1. To calculate the percentage uncertainty in results
  2. To determine whether the hypothesis is supported
  3. To decide which graph to plot
  4. To identify hazards and describe measures to reduce the risk of harm Correct answer.

Explanation

A risk assessment identifies potential hazards in an investigation and specifies controls to reduce the likelihood or severity of harm. It is a safety planning document rather than a data-analysis tool. Uncertainty, graphing, and hypothesis testing are separate parts of the investigation.

Question 25Science Inquiry Skills

A student uses a ruler to measure the length of a block and records 6.35 cm. The ruler has millimetre markings. Which statement about this recording is most appropriate?

  1. The reading is invalid because rulers cannot measure length
  2. The extra digit is justified because rulers are highly precise
  3. The extra digit is unjustified because the ruler cannot resolve to 0.01 cm Correct answer.
  4. The reading should be rounded to 6 m

Explanation

A ruler with millimetre markings can be read to about 0.1 cm, so recording 6.35 cm implies a resolution of 0.01 cm that the instrument does not have. The value should be recorded to an appropriate number of significant figures, such as 6.4 cm. Extra digits suggest false precision.

Question 26Science Inquiry Skills

In a physics experiment, a student changes the mass on a spring and measures the resulting extension. Which variable is the independent variable?

  1. The mass on the spring Correct answer.
  2. The acceleration due to gravity
  3. The spring constant
  4. The extension of the spring

Explanation

The independent variable is the one that the experimenter deliberately changes. Here the student changes the mass, so mass is the independent variable. The extension is the dependent variable because it responds to the change in mass.

Question 27Science Inquiry Skills

A student measures the length of a pendulum five times and obtains slightly different values each time. Which term best describes this type of variation?

  1. Zero error
  2. Parallax error
  3. Systematic error
  4. Random error Correct answer.

Explanation

Random errors cause measurements to scatter unpredictably around a mean value. They arise from unpredictable fluctuations such as reaction time or small environmental changes. Systematic errors, by contrast, shift all readings in the same direction.

Question 28Science Inquiry Skills

A student records the volume of a liquid as 25.0 mL using a measuring cylinder with 1 mL graduations. Which statement correctly describes the precision of this measurement?

  1. The precision is 25 mL because that is the recorded value.
  2. The precision is 0.1 mL because the cylinder can be read to one decimal place.
  3. The precision is 1 mL because that is the smallest graduation.
  4. The precision is 0.5 mL because the smallest graduation is 1 mL. Correct answer.

Explanation

When using an analogue scale, the uncertainty is typically half the smallest graduation. With 1 mL graduations, the precision is therefore 0.5 mL. This reflects the limit of reading between the marks.

Question 29Science Inquiry Skills

Which of the following is the most appropriate unit to express the uncertainty in a time measurement recorded with a stopwatch reading to 0.01 s?

  1. Newtons
  2. Metres
  3. Seconds Correct answer.
  4. Joules

Explanation

Uncertainty has the same unit as the quantity being measured. Since time is measured in seconds, its uncertainty is also expressed in seconds. Other units like metres, newtons, or joules measure different quantities.

Question 30Science Inquiry Skills

A student plots a graph of force versus extension for a spring and obtains a straight line through the origin. What does the gradient of this graph represent?

  1. The total work done
  2. The elastic potential energy
  3. The extension per unit force
  4. The spring constant Correct answer.

Explanation

Hooke's law states that force is proportional to extension, F = kx. A graph of F against x therefore has gradient k, the spring constant. The gradient's units are N/m, confirming it is a stiffness.

Question 31Science Inquiry Skills

A student measures the diameter of a wire with a micrometer and obtains 0.84 mm. The micrometer has a zero error of +0.02 mm. What is the corrected diameter?

  1. 0.84 mm
  2. 0.80 mm
  3. 0.82 mm Correct answer.
  4. 0.86 mm

Explanation

A positive zero error means the instrument reads a value greater than the true value when measuring zero. To correct, subtract the zero error from the measured reading: 0.84 mm − 0.02 mm = 0.82 mm. This adjustment removes the systematic offset.

Question 32Science Inquiry Skills

A student calculates the area of a rectangle from measurements of length 5.0 ± 0.1 cm and width 3.0 ± 0.1 cm. What is the percentage uncertainty in the area?

  1. Approximately 5% Correct answer.
  2. Approximately 10%
  3. Approximately 2%
  4. Approximately 3%

Explanation

When multiplying quantities, percentage uncertainties add. The length has 0.1/5.0 = 2% uncertainty and the width has 0.1/3.0 ≈ 3.3% uncertainty. The sum is about 5.3%, closest to 5%.

Question 33Science Inquiry Skills

Which of the following best describes the difference between accuracy and precision?

  1. Accuracy is the smallest scale division; precision is the number of decimal places.
  2. Accuracy is freedom from random error; precision is freedom from systematic error.
  3. Accuracy is closeness of repeated readings; precision is closeness to the true value.
  4. Accuracy is closeness to the true value; precision is closeness of repeated readings to each other. Correct answer.

Explanation

Accuracy refers to how close a measured value is to the accepted or true value. Precision refers to how close repeated measurements are to each other, regardless of their closeness to the true value. A measurement can be precise but inaccurate if a systematic error is present.

Question 34Science Inquiry Skills

A student investigates how the period of a pendulum depends on its length. Which of the following is the most appropriate way to improve the reliability of the period measurement?

  1. Perform the experiment at a different location.
  2. Use a heavier pendulum bob.
  3. Measure the length with a more precise ruler.
  4. Time multiple swings and divide by the number of swings. Correct answer.

Explanation

Reliability is improved by reducing the effect of random errors, often through repetition or averaging. Timing many swings and dividing reduces the relative impact of human reaction time on each period. Using a heavier bob or a more precise ruler addresses other factors, not the reliability of the period measurement.

Question 35Science Inquiry Skills

A student obtains the following repeated measurements for a length: 12.3 cm, 12.4 cm, 12.2 cm, 12.3 cm, and 12.3 cm. What is the best estimate of the length?

  1. 12.3 cm Correct answer.
  2. 12.2 cm
  3. 12.0 cm
  4. 12.4 cm

Explanation

The best estimate from repeated measurements is the mean. The sum is 61.5 cm, and dividing by 5 gives 12.3 cm. This central value is the most reliable estimate of the true length.

Question 36Science Inquiry Skills

Which of the following is the most appropriate way to reduce the effect of random errors in an experiment?

  1. Repeat the measurement several times and average the results. Correct answer.
  2. Calibrate the instrument to remove zero error.
  3. Change the independent variable more widely.
  4. Use a more sensitive instrument.

Explanation

Random errors cause scatter around a mean, and averaging repeated measurements reduces their influence. Calibration addresses systematic errors, while sensitivity and range changes affect other aspects. Averaging is the standard method for reducing random error.

Question 37Science Inquiry Skills

A student measures the current through a resistor as 0.50 A when the voltage is 6.0 V. What is the resistance of the resistor?

  1. 6.5 Ω
  2. 0.083 Ω
  3. 12 Ω Correct answer.
  4. 3.0 Ω

Explanation

Ohm's law states that V = IR, so R = V/I. Substituting gives R = 6.0 V / 0.50 A = 12 Ω. The units are ohms, consistent with resistance.

Question 38Science Inquiry Skills

A student plots a graph of the square of the period T² of a simple pendulum against its length L. The graph is a straight line through the origin. What does the gradient represent?

  1. 4π²/g Correct answer.
  2. g
  3. g/4π²
  4. 2π/g

Explanation

The period of a simple pendulum is given by T = 2π√(L/g). Squaring both sides gives T² = (4π²/g)L. A graph of T² against L therefore has gradient 4π²/g.

Question 39Science Inquiry Skills

Which of the following best describes a hypothesis in a physics investigation?

  1. A summary of the experimental method.
  2. A final conclusion supported by data.
  3. A testable prediction that relates the independent and dependent variables. Correct answer.
  4. A statement that is always true regardless of evidence.

Explanation

A hypothesis is a proposed explanation or prediction that can be tested by experiment. It typically predicts how a change in the independent variable will affect the dependent variable. It must be falsifiable, meaning that evidence could show it to be wrong.

Question 40Science Inquiry Skills

A student measures the mass of an object as 50.0 g and its volume as 20.0 cm³. What is the density of the object?

  1. 0.400 g/cm³
  2. 2.50 g/cm³ Correct answer.
  3. 70.0 g/cm³
  4. 30.0 g/cm³

Explanation

Density is mass divided by volume. Substituting gives 50.0 g / 20.0 cm³ = 2.50 g/cm³. The units are grams per cubic centimetre, consistent with density.

Question 41Science Inquiry Skills

A student investigates the relationship between the force applied to a spring and its extension. Which of the following is the most appropriate graph to plot to obtain a straight line?

  1. Extension on the y-axis against force squared on the x-axis
  2. Extension on the y-axis against force on the x-axis
  3. Force on the y-axis against extension on the x-axis Correct answer.
  4. Force on the y-axis against extension squared on the x-axis

Explanation

Hooke's law states that force is directly proportional to extension, F = kx. Plotting force against extension gives a straight line through the origin with gradient equal to the spring constant. This is the standard way to test Hooke's law.

Question 42Science Inquiry Skills

A student uses a metre ruler to measure the length of a pendulum. The ruler has millimetre markings. Which of the following is the most appropriate way to record the length?

  1. Record to the nearest centimetre with an uncertainty of ±1 cm.
  2. Record to the nearest micrometre with an uncertainty of ±0.5 µm.
  3. Record to the nearest millimetre with an uncertainty of ±0.5 mm. Correct answer.
  4. Record to the nearest metre with an uncertainty of ±0.5 m.

Explanation

The precision of an analogue scale is typically half the smallest graduation. With millimetre markings, the length should be recorded to the nearest millimetre with an uncertainty of ±0.5 mm. This reflects the limit of reading the scale.

Question 43Science Inquiry Skills

Which of the following best explains why a control group is included in an experiment?

  1. To ensure that all variables are changed at once.
  2. To provide a baseline for comparison so the effect of the independent variable can be isolated. Correct answer.
  3. To reduce the cost of the experiment.
  4. To increase the number of measurements taken.

Explanation

A control group is not exposed to the independent variable, providing a baseline against which the experimental group is compared. This helps isolate the effect of the independent variable from other factors. Without a control, it is difficult to attribute changes to the independent variable.

Question 44Science Inquiry Skills

A student measures the voltage across a resistor as 4.0 ± 0.1 V and the current through it as 0.20 ± 0.01 A. What is the resistance and its absolute uncertainty?

  1. 20 ± 2 Ω
  2. 20 ± 0.1 Ω
  3. 20 ± 0.5 Ω
  4. 20 ± 1 Ω Correct answer.

Explanation

Resistance is R = V/I = 4.0/0.20 = 20 Ω. The percentage uncertainty in V is 0.1/4.0 = 2.5% and in I is 0.01/0.20 = 5%. Adding gives 7.5%, so the absolute uncertainty is 0.075 × 20 = 1.5 Ω, approximately 1 Ω when rounded to one significant figure.

Question 45Science Inquiry Skills

A student plots a graph of ln(T) against ln(L) for a pendulum and obtains a straight line with gradient 0.5. What does this indicate about the relationship between T and L?

  1. T is proportional to L.
  2. T is proportional to L squared.
  3. T is independent of L.
  4. T is proportional to the square root of L. Correct answer.

Explanation

Taking logarithms of a power-law relationship T = kL^n gives ln(T) = ln(k) + n ln(L). The gradient of a graph of ln(T) against ln(L) is therefore the exponent n. A gradient of 0.5 means T ∝ L^0.5, i.e. T is proportional to the square root of L.

Question 46Science Inquiry Skills

A student measures the period of a pendulum as 2.0 s using a stopwatch with a reaction time of 0.2 s. What is the percentage uncertainty in the period?

  1. 20%
  2. 1%
  3. 0.1%
  4. 10% Correct answer.

Explanation

Percentage uncertainty is (absolute uncertainty / measured value) × 100%. Here it is (0.2 / 2.0) × 100% = 10%. This shows the reaction time is a significant source of error for a single short timing.

Question 47Science Inquiry Skills

A student obtains the following data for the extension of a spring: force 1.0 N gives 2.0 cm, 2.0 N gives 4.0 cm, 3.0 N gives 6.0 cm, and 4.0 N gives 9.0 cm. Which statement best describes the data?

  1. The data are linear throughout the entire range.
  2. The data are linear up to 3.0 N, after which the spring may have exceeded its elastic limit. Correct answer.
  3. The data show an inversely proportional relationship.
  4. The data show that the spring constant is decreasing from the start.

Explanation

The first three points show a constant ratio of 2.0 cm/N, indicating Hooke's law is obeyed. The fourth point deviates from this ratio, suggesting the spring has passed its elastic limit. This is a common analysis in spring experiments.

Question 48Science Inquiry Skills

Which of the following best describes the purpose of a risk assessment in a physics investigation?

  1. To calculate the uncertainty in measurements.
  2. To identify hazards and outline measures to reduce the risk of harm. Correct answer.
  3. To determine the independent variable.
  4. To ensure that the experiment produces valid results.

Explanation

A risk assessment identifies potential hazards in an experiment and specifies control measures to minimise the risk of injury. It is a safety document, not a tool for data analysis or experimental design. Its focus is on protecting people and the environment.

Question 49Science Inquiry Skills

A student measures the diameter of a sphere as 2.0 ± 0.1 cm. What is the percentage uncertainty in the volume of the sphere?

  1. 15% Correct answer.
  2. 5%
  3. 30%
  4. 10%

Explanation

The volume of a sphere is V = (4/3)πr³, so the percentage uncertainty in V is three times the percentage uncertainty in r. The radius is 1.0 ± 0.05 cm, giving 5% uncertainty in r. Therefore the volume has 3 × 5% = 15% uncertainty.

Question 50Science Inquiry Skills

Which of the following best describes the difference between a systematic error and a random error?

  1. A systematic error can be reduced by averaging, while a random error cannot.
  2. A systematic error is always larger than a random error.
  3. A systematic error shifts all readings in the same direction, while a random error causes scatter around a mean. Correct answer.
  4. A systematic error causes scatter around a mean, while a random error shifts all readings in the same direction.

Explanation

Systematic errors, such as zero error or incorrect calibration, affect all measurements in a consistent way. Random errors, such as fluctuations in reaction time, cause unpredictable variation. Averaging reduces random error but does not remove systematic error.