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NSSCO Physics (6118) study materials
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NSSCO Physics (6118) practice questions

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Question 1Measurement and Units

Which of the following is the SI base unit of mass?

  1. Gram
  2. Pound
  3. Kilogram Correct answer.
  4. Newton

Explanation

Mass is one of the seven SI base quantities and its base unit is the kilogram, so every other mass unit is defined by reference to it. The gram is exactly one thousandth of a kilogram, which makes it a submultiple rather than the base unit itself.

Question 2Measurement and Units

A capacitor is labelled 4.7 µF. Which value expresses this capacitance in farads in standard form?

  1. 4.7 × 10⁻⁹ F
  2. 4.7 × 10⁶ F
  3. 4.7 × 10⁻³ F
  4. 4.7 × 10⁻⁶ F Correct answer.

Explanation

The prefix micro represents one millionth, that is 10⁻⁶, so a value of 4.7 µF is written as 4.7 × 10⁻⁶ F. The neighbouring prefixes are milli (10⁻³), nano (10⁻⁹) and mega (10⁶), none of which applies to the symbol µ.

Question 3Measurement and Units

A student must measure the thickness of a single sheet of paper as precisely as possible. Which instrument is most suitable?

  1. Tape measure
  2. Micrometer Correct answer.
  3. Metre rule
  4. Vernier caliper

Explanation

A micrometer screw gauge resolves to 0.01 mm, which is fine enough to detect the small differences in thickness involved here. A metre rule resolves to about 1 mm and a vernier caliper to about 0.1 mm, so neither can measure a sheet only about 0.1 mm thick with useful precision.

Question 4Measurement and Units

A vernier caliper has a main scale graduated in millimetres and a vernier scale whose 10 divisions cover exactly 9 mm. The vernier zero lies between the 23 mm and 24 mm marks, and the sixth vernier division coincides exactly with a main-scale mark. What is the reading?

  1. 23.4 mm
  2. 23.6 mm Correct answer.
  3. 24.6 mm
  4. 23.06 mm

Explanation

The reading is the main-scale value immediately before the vernier zero plus the coinciding vernier division multiplied by the least count. Ten vernier divisions spanning 9 mm give a least count of 0.1 mm, so the sixth division adds 0.6 mm to the 23 mm already passed, giving 23.6 mm.

Question 5Measurement and Units

Which combination of SI base units is equivalent to the newton?

  1. kg·m·s⁻² Correct answer.
  2. kg·s⁻²
  3. kg·m·s⁻¹
  4. kg·m²·s⁻²

Explanation

One newton is the force that gives a 1 kg mass an acceleration of 1 m/s², so 1 N = 1 kg × 1 m·s⁻² = kg·m·s⁻². Any other combination of base units given here fails to reproduce the dimensions of force, which must contain mass, length and inverse time squared.

Question 6Measurement and Units

A rectangular plate measures 12.4 cm by 3.0 cm. Applying the rules for significant figures, what is the area of the plate?

  1. 37.2 cm²
  2. 37.20 cm²
  3. 37 cm² Correct answer.
  4. 40 cm²

Explanation

When quantities are multiplied, the answer is quoted to the same number of significant figures as the factor with the fewest, and here 3.0 cm carries only two. The arithmetic gives 37.2 cm², which rounds to 37 cm².

Question 7Measurement and Units

An irregular stone of mass 54.0 g is lowered into a measuring cylinder containing 40 cm³ of water, and the water level rises to 60 cm³. What is the density of the stone?

  1. 3.00 g/cm³
  2. 2.70 g/cm³ Correct answer.
  3. 1.35 g/cm³
  4. 0.90 g/cm³

Explanation

The stone displaces its own volume of water, so its volume equals the rise in the water level, 60 cm³ − 40 cm³ = 20 cm³. Density is mass divided by volume, giving 54.0 g ÷ 20 cm³ = 2.70 g/cm³.

Question 8Measurement and Units

A car travels along a straight road at a steady speed of 90 km/h. What is this speed in metres per second?

  1. 324 m/s
  2. 25 m/s Correct answer.
  3. 1.5 m/s
  4. 32 m/s

Explanation

To change from km/h to m/s, multiply by 1000 m per km and divide by 3600 s per hour, which is the same as dividing by 3.6. Therefore 90 km/h equals 90 ÷ 3.6 = 25 m/s.

Question 9Measurement and Units

A micrometer screw gauge has a zero error of +0.03 mm. When it is used to measure the diameter of a wire, the reading obtained is 2.45 mm. What is the corrected diameter of the wire?

  1. 2.48 mm
  2. 2.45 mm
  3. 2.75 mm
  4. 2.42 mm Correct answer.

Explanation

A zero error shifts every reading by the same amount, so a positive zero error means the instrument reads too high and the error must be subtracted. Corrected diameter = 2.45 mm − 0.03 mm = 2.42 mm.

Question 10Measurement and Units

The drag force F on an object moving through a fluid is modelled as F = k v², where v is the speed of the object and k is a constant. What are the SI base units of k?

  1. kg·m⁻²
  2. kg·m·s⁻¹
  3. kg·s⁻¹
  4. kg·m⁻¹ Correct answer.

Explanation

Rearranging the equation gives k = F ÷ v², so the units of k are those of force divided by the units of speed squared. Dividing kg·m·s⁻² by m²·s⁻² cancels the s⁻² terms and leaves kg·m⁻¹.

Question 11Measurement and Units

A radio station broadcasts at a frequency of 96.5 MHz. Which value is equivalent to this frequency?

  1. 9.65 × 10^7 Hz Correct answer.
  2. 9.65 × 10^8 Hz
  3. 9.65 × 10^6 Hz
  4. 9.65 × 10^5 Hz

Explanation

The prefix mega (M) means 10^6, so 96.5 MHz is 96.5 × 10^6 Hz. Writing this in standard form gives 9.65 × 10^7 Hz.

Question 12Measurement and Units

The pascal (Pa) is the SI unit of pressure. Which combination of SI base units is equivalent to the pascal?

  1. kg m² s⁻²
  2. kg m⁻² s⁻²
  3. kg m⁻¹ s⁻² Correct answer.
  4. kg m s⁻²

Explanation

Pressure is force divided by area, and force is measured in kg m s⁻². Dividing by area in m² gives kg m⁻¹ s⁻², which is the pascal.

Question 13Measurement and Units

A rectangular floor has an area of 1.5 m². What is this area in square centimetres?

  1. 150 cm²
  2. 150 000 cm²
  3. 15 000 cm² Correct answer.
  4. 1 500 cm²

Explanation

Since 1 m = 100 cm, one square metre contains 100 × 100 = 10 000 cm². Multiplying 1.5 m² by 10 000 gives 15 000 cm².

Question 14Measurement and Units

A metal block has a mass of 240 g and a volume of 30 cm³. What is the density of the metal in kg/m³?

  1. 80 kg/m³
  2. 80 000 kg/m³
  3. 800 kg/m³
  4. 8 000 kg/m³ Correct answer.

Explanation

Density is mass divided by volume, so the density is 240 g ÷ 30 cm³ = 8 g/cm³. Because 1 g/cm³ equals 1000 kg/m³, the density is 8 × 1000 = 8000 kg/m³.

Question 15Measurement and Units

How many significant figures are there in the measurement 0.02050 m?

  1. 4 Correct answer.
  2. 3
  3. 2
  4. 5

Explanation

Leading zeros are not significant, but the digits 2, 0, 5 and the final 0 are significant. Therefore the measurement 0.02050 m has four significant figures.

Question 16Measurement and Units

The pressure difference Δp across a section of pipe is assumed to depend on the density ρ and speed v of the fluid according to Δp = k ρ^a v^b, where k is dimensionless. What are the values of a and b?

  1. a = 1, b = 1
  2. a = 2, b = 1
  3. a = 1, b = 2 Correct answer.
  4. a = 2, b = 2

Explanation

Pressure has base units kg m⁻¹ s⁻², density has kg m⁻³ and speed has m s⁻¹. Equating the powers of kg, m and s gives a = 1 and b = 2.

Question 17Kinematics and Dynamics: Motion, Forces and Momentum

Which of the following quantities is a vector?

  1. Mass
  2. Speed
  3. Distance
  4. Velocity Correct answer.

Explanation

Velocity has both magnitude and direction, so it is a vector quantity. Distance, speed and mass have magnitude only and are therefore scalars. A change of direction changes velocity even when the speed stays constant.

Question 18Kinematics and Dynamics: Motion, Forces and Momentum

A passenger standing in a bus is thrown forward when the driver brakes suddenly. Which statement explains this?

  1. The passenger's inertia keeps them moving forward. Correct answer.
  2. A forward force from the brakes pushes the passenger.
  3. Air resistance inside the bus pushes the passenger.
  4. The passenger's weight increases as the bus slows down.

Explanation

By Newton's first law, a body continues in uniform motion unless a resultant force acts on it. When the bus decelerates, the passenger keeps moving forward at the original speed, so the passenger appears to be thrown forward. No forward force actually acts on the passenger.

Question 19Kinematics and Dynamics: Motion, Forces and Momentum

A cyclist travels 150 m along a straight road in 25 s at constant speed. What is the speed of the cyclist?

  1. 0.17 m/s
  2. 6.0 m/s Correct answer.
  3. 3.75 m/s
  4. 3750 m/s

Explanation

Speed equals distance divided by time, so 150 m ÷ 25 s = 6.0 m/s. Rearranging the equation s = vt gives the same value, and the unit is metres per second.

Question 20Kinematics and Dynamics: Motion, Forces and Momentum

A car accelerates uniformly from rest to 20 m/s in 10 s, then travels at a constant 20 m/s for 15 s. What is the total distance covered?

  1. 400 m Correct answer.
  2. 300 m
  3. 500 m
  4. 200 m

Explanation

The distance travelled equals the area under the velocity-time graph. The acceleration stage is a triangle of area ½ × 10 × 20 = 100 m, and the constant-speed stage is a rectangle of area 20 × 15 = 300 m, giving 400 m in total.

Question 21Kinematics and Dynamics: Motion, Forces and Momentum

A car accelerates uniformly from 8 m/s to 20 m/s in 4.0 s. What is its acceleration?

  1. 3.0 m/s² Correct answer.
  2. 7.0 m/s²
  3. 2.0 m/s²
  4. 5.0 m/s²

Explanation

Acceleration is the change in velocity divided by the time taken: (20 − 8) ÷ 4.0 = 3.0 m/s². The car gains 3.0 m/s of speed every second during this interval.

Question 22Kinematics and Dynamics: Motion, Forces and Momentum

Trolley A of mass 2.0 kg moves at 3.0 m/s and collides with trolley B of mass 3.0 kg, which is at rest. The trolleys stick together after the collision. What is their common velocity?

  1. 1.2 m/s Correct answer.
  2. 1.8 m/s
  3. 2.0 m/s
  4. 0.80 m/s

Explanation

Total momentum before the collision is (2.0 × 3.0) + (3.0 × 0) = 6.0 kg m/s. Momentum is conserved, so the combined 5.0 kg moves at 6.0 ÷ 5.0 = 1.2 m/s.

Question 23Kinematics and Dynamics: Motion, Forces and Momentum

An object has a mass of 5.0 kg. On a planet where the gravitational field strength is 3.8 N/kg, what is the weight of the object?

  1. 5.0 N
  2. 49 N
  3. 19 N Correct answer.
  4. 1.3 N

Explanation

Weight equals mass multiplied by gravitational field strength: W = mg = 5.0 × 3.8 = 19 N. The mass stays 5.0 kg everywhere, but the weight changes with the local value of g.

Question 24Kinematics and Dynamics: Motion, Forces and Momentum

A 4.0 kg box is pushed across a horizontal floor with a force of 12 N. A constant friction force of 4 N acts on the box. What is the acceleration of the box?

  1. 1.0 m/s²
  2. 2.0 m/s² Correct answer.
  3. 4.0 m/s²
  4. 3.0 m/s²

Explanation

The resultant force is 12 − 4 = 8 N in the direction of the push. Using F = ma gives a = 8 ÷ 4.0 = 2.0 m/s².

Question 25Kinematics and Dynamics: Motion, Forces and Momentum

A stone is thrown vertically upwards at 15 m/s from the top of a cliff 20 m high. Taking g = 10 m/s² and ignoring air resistance, what is the speed of the stone just before it hits the ground below?

  1. 20 m/s
  2. 30 m/s
  3. 25 m/s Correct answer.
  4. 35 m/s

Explanation

Take upward as positive: the stone leaves at +15 m/s and lands 20 m lower, so s = −20 m. Using v² = u² + 2as with a = −10 m/s² gives v² = 225 + 400 = 625, so v = 25 m/s downwards.

Question 26Kinematics and Dynamics: Motion, Forces and Momentum

A ball of mass 0.20 kg hits a wall at 8.0 m/s and rebounds along the same line at 6.0 m/s. The contact time with the wall is 0.020 s. What is the average force exerted by the wall on the ball?

  1. 20 N
  2. 280 N
  3. 14 N
  4. 140 N Correct answer.

Explanation

Take the rebound direction as positive: initial momentum is 0.20 × (−8.0) = −1.6 kg m/s and final momentum is 0.20 × 6.0 = +1.2 kg m/s. The change is 2.8 kg m/s, so F = Δp ÷ t = 2.8 ÷ 0.020 = 140 N.

Question 27Kinematics and Dynamics: Motion, Forces and Momentum

A runner completes exactly one lap of a circular track of circumference 400 m and stops at the starting point. Which statement about the runner's distance and displacement is correct?

  1. The distance is 400 m and the displacement is zero. Correct answer.
  2. Both distance and displacement are 400 m.
  3. The distance is zero and the displacement is 400 m.
  4. Both distance and displacement are zero.

Explanation

Distance is the total length of path travelled, so one full lap gives 400 m. Displacement is the straight-line change in position from start to finish; because the runner returns to the starting point, this change is zero.

Question 28Kinematics and Dynamics: Motion, Forces and Momentum

A velocity–time graph for an object moving in a straight line is a horizontal line above the time axis. Which description of the motion is correct?

  1. It moves with constant acceleration.
  2. Its speed increases steadily.
  3. It moves at constant velocity. Correct answer.
  4. It remains at rest.

Explanation

The gradient of a velocity–time graph gives acceleration. A horizontal line has zero gradient, so acceleration is zero, while the line being above the axis means the velocity is constant and positive.

Question 29Kinematics and Dynamics: Motion, Forces and Momentum

Which statement correctly distinguishes mass from weight?

  1. Mass changes when the body moves, but weight stays the same.
  2. Mass is matter in a body; weight is gravitational force on it. Correct answer.
  3. Mass is measured in newtons, but weight is measured in kilograms.
  4. Mass is a force on the body, but weight is the amount of matter.

Explanation

Mass is a scalar measure of the amount of matter, measured in kilograms. Weight is the gravitational force on a body, measured in newtons, and it changes when gravitational field strength changes.

Question 30Kinematics and Dynamics: Motion, Forces and Momentum

A 1 200 kg car experiences a resultant forward force of 3 600 N. What is the acceleration of the car?

  1. 1.2 m/s²
  2. 0.33 m/s²
  3. 3.6 m/s²
  4. 3.0 m/s² Correct answer.

Explanation

Newton's second law gives acceleration as resultant force divided by mass. Using a = F/m = 3600 N / 1200 kg gives 3.0 m/s².

Question 31Kinematics and Dynamics: Motion, Forces and Momentum

A ball is released from rest and falls freely for 3.0 s. Taking g = 9.8 m/s² and ignoring air resistance, how far has it fallen?

  1. 88 m
  2. 44 m Correct answer.
  3. 29 m
  4. 150 m

Explanation

Using s = ut + ½at² with u = 0 gives s = ½ × 9.8 × 3.0² = 44.1 m. To two significant figures this is 44 m.

Question 32Kinematics and Dynamics: Motion, Forces and Momentum

A resultant force of 20 N acts for 0.50 s on a 4.0 kg trolley initially at rest. What is the final speed of the trolley?

  1. 10 m/s
  2. 5.0 m/s
  3. 0.40 m/s
  4. 2.5 m/s Correct answer.

Explanation

Impulse is force multiplied by time, so Ft = 20 × 0.50 = 10 N s. This equals the change in momentum, giving Δv = 10 / 4.0 = 2.5 m/s.

Question 33Kinematics and Dynamics: Motion, Forces and Momentum

A skydiver falls vertically at constant terminal velocity. Which statement about the forces on the skydiver is correct?

  1. The air resistance is greater than the weight, so the skydiver slows down.
  2. The weight and air resistance are equal in size and opposite in direction. Correct answer.
  3. There are no forces acting on the skydiver.
  4. The weight is greater than the air resistance, so the skydiver still accelerates.

Explanation

At terminal velocity the skydiver's velocity is constant, so acceleration is zero. The resultant force must be zero, meaning the downward weight is balanced by the upward air resistance.

Question 34Kinematics and Dynamics: Motion, Forces and Momentum

A book rests on a horizontal table. Which pair of forces is an example of a Newton's third law pair?

  1. The normal force from the table on the book and the weight of the table
  2. The weight of the book and the gravitational force of the book on the Earth Correct answer.
  3. The weight of the book and the normal force from the table on the book
  4. The normal force from the table on the book and the friction between the book and the table

Explanation

A Newton's third law pair consists of two equal and opposite forces of the same type acting on different bodies. The Earth pulls the book down with its weight, and the book pulls the Earth up with an equal gravitational force.

Question 35Kinematics and Dynamics: Motion, Forces and Momentum

A 0.50 kg ball moving at 4.0 m/s to the right collides head-on with a 0.30 kg ball at rest. After the collision, the 0.50 kg ball moves at 1.0 m/s to the right. What is the velocity of the 0.30 kg ball after the collision?

  1. 3.0 m/s to the left
  2. 1.5 m/s to the right
  3. 5.0 m/s to the right Correct answer.
  4. 6.7 m/s to the right

Explanation

Total momentum before the collision is 0.50 × 4.0 = 2.0 kg m/s to the right. After the collision the 0.50 kg ball has momentum 0.50 × 1.0 = 0.50 kg m/s, so the 0.30 kg ball must have 1.5 kg m/s. Its velocity is 1.5 / 0.30 = 5.0 m/s to the right.

Question 36Kinematics and Dynamics: Motion, Forces and Momentum

A car travels the first half of a journey at 20 m/s and the second half of the same distance at 30 m/s. What is its average speed for the whole journey?

  1. 24 m/s Correct answer.
  2. 25 m/s
  3. 50 m/s
  4. 26 m/s

Explanation

Average speed is total distance divided by total time, not the mean of the two speeds. For equal distances d, the times are d/20 and d/30, so average speed = 2d / (d/20 + d/30) = 24 m/s.

Question 37Kinematics and Dynamics: Motion, Forces and Momentum

On a distance-time graph for an object moving in a straight line, what does the gradient of the line represent?

  1. Distance travelled
  2. Speed Correct answer.
  3. Acceleration
  4. Resultant force

Explanation

The gradient of a distance-time graph is found by dividing a change in distance by the corresponding change in time, which is speed. A steeper straight line therefore means a greater constant speed.

Question 38Kinematics and Dynamics: Motion, Forces and Momentum

An object is moving in a straight line when the resultant force acting on it becomes zero. What happens to the object?

  1. It accelerates at a constant rate.
  2. It slows down and stops.
  3. It continues at constant velocity. Correct answer.
  4. It reverses direction.

Explanation

By Newton's first law, a zero resultant force means the object has no acceleration. It therefore keeps moving with the same velocity, including the same direction, until an unbalanced force acts.

Question 39Kinematics and Dynamics: Motion, Forces and Momentum

Which unit is equivalent to the newton second (N s)?

  1. kg m s⁻²
  2. kg m s⁻¹ Correct answer.
  3. kg m² s⁻²
  4. kg m⁻¹ s⁻¹

Explanation

The newton second is the unit of impulse, and impulse equals change in momentum. Since momentum is mass times velocity, its unit is kg × m/s, which is kg m s⁻¹.

Question 40Kinematics and Dynamics: Motion, Forces and Momentum

A rifle of mass 4.0 kg fires a bullet of mass 0.020 kg at a horizontal speed of 300 m/s. What is the magnitude of the recoil speed of the rifle?

  1. 6.0 m/s
  2. 0.67 m/s
  3. 0.15 m/s
  4. 1.5 m/s Correct answer.

Explanation

Before firing the total momentum is zero, so the bullet and rifle must have equal and opposite momenta afterwards. The bullet momentum is 0.020 × 300 = 6.0 kg m/s, so the rifle recoils at 6.0 / 4.0 = 1.5 m/s.

Question 41Kinematics and Dynamics: Motion, Forces and Momentum

A car travelling at 20 m/s brakes uniformly and stops in a distance of 40 m. What is the magnitude of its acceleration while braking?

  1. 20 m/s²
  2. 2.5 m/s²
  3. 5.0 m/s² Correct answer.
  4. 10 m/s²

Explanation

Using v² = u² + 2as with v = 0, u = 20 m/s and s = 40 m gives 0 = 400 + 80a, so a = -5.0 m/s². The magnitude is therefore 5.0 m/s².

Question 42Kinematics and Dynamics: Motion, Forces and Momentum

A passenger of mass 60 kg stands in a lift that accelerates upwards at 2.0 m/s². Taking g = 10 N/kg, what is the normal force exerted by the floor on the passenger?

  1. 720 N Correct answer.
  2. 480 N
  3. 840 N
  4. 600 N

Explanation

The resultant upward force is the normal force minus weight: R - mg = ma. Thus R = 60 × 10 + 60 × 2.0 = 600 + 120 = 720 N.

Question 43Kinematics and Dynamics: Motion, Forces and Momentum

Two horizontal forces of 6.0 N and 8.0 N act at right angles to each other on a 2.0 kg object. What is the magnitude of the object's acceleration?

  1. 5.0 m/s² Correct answer.
  2. 7.0 m/s²
  3. 3.0 m/s²
  4. 10 m/s²

Explanation

The resultant of two perpendicular forces is found with Pythagoras: √(6.0² + 8.0²) = 10 N. Newton's second law then gives a = F/m = 10/2.0 = 5.0 m/s².

Question 44Kinematics and Dynamics: Motion, Forces and Momentum

An object moving in a straight line with uniform acceleration passes point A at 4.0 m/s and point B, 20 m away, at 12 m/s. How long does it take to travel from A to B?

  1. 1.67 s
  2. 2.5 s Correct answer.
  3. 2.0 s
  4. 1.25 s

Explanation

For uniform acceleration the average velocity is (u + v)/2 = (4.0 + 12)/2 = 8.0 m/s. The time is distance divided by average velocity: 20/8.0 = 2.5 s.

Question 45Kinematics and Dynamics: Motion, Forces and Momentum

A ball rolls horizontally off the edge of a table at 4.0 m/s. The table is 1.25 m high. Taking g = 10 m/s² and ignoring air resistance, how far from the base of the table does the ball land?

  1. 2.5 m
  2. 2.0 m Correct answer.
  3. 1.0 m
  4. 4.0 m

Explanation

The vertical fall is independent of the horizontal motion. Using s = ½gt² gives 1.25 = 5t², so t = 0.50 s; the horizontal distance is then 4.0 × 0.50 = 2.0 m.

Question 46Kinematics and Dynamics: Motion, Forces and Momentum

A 5.0 kg box is pulled along a horizontal floor by a rope inclined at 30° above the horizontal. The tension in the rope is 20 N and a constant friction force of 5.0 N acts on the box. What is the acceleration of the box?

  1. 4.0 m/s²
  2. 1.5 m/s²
  3. 3.0 m/s²
  4. 2.5 m/s² Correct answer.

Explanation

Only the horizontal component of the tension drives the box forward: T cos30° = 20 × 0.866 ≈ 17.3 N. The resultant horizontal force is 17.3 - 5.0 = 12.3 N, so a = 12.3/5.0 ≈ 2.5 m/s².

Question 47Kinematics and Dynamics: Motion, Forces and Momentum

A student lists four quantities used to describe motion: mass, speed, distance and velocity. Which listed quantity is a vector?

  1. Distance
  2. Mass
  3. Velocity Correct answer.
  4. Speed

Explanation

A vector quantity has both magnitude and direction. Velocity is the only quantity in the list that must include a direction as well as a size. Mass, speed and distance are scalars and are fully described by magnitude alone.

Question 48Kinematics and Dynamics: Motion, Forces and Momentum

A shopper walks 6.0 m east along a straight aisle, then turns around and walks 8.0 m west. What is the shopper's displacement from the starting point?

  1. 14 m east
  2. 2.0 m west Correct answer.
  3. 2.0 m east
  4. 14 m west

Explanation

Displacement is a vector, so opposite directions have opposite signs. Taking east as positive gives +6.0 m − 8.0 m = −2.0 m, which is 2.0 m west. The total distance walked is 14 m, but distance is not displacement.

Question 49Kinematics and Dynamics: Motion, Forces and Momentum

A cyclist's velocity increases uniformly from 4.0 m/s to 10 m/s in 3.0 s. What is the magnitude of the cyclist's acceleration?

  1. 4.7 m/s²
  2. 1.5 m/s²
  3. 2.0 m/s² Correct answer.
  4. 1.0 m/s²

Explanation

Acceleration is the change in velocity divided by the time taken. Here a = (10 − 4.0)/3.0 = 2.0 m/s². Because the velocity increases, the acceleration acts in the direction of motion.

Question 50Kinematics and Dynamics: Motion, Forces and Momentum

A car's velocity–time graph is a straight line from 4.0 m/s at t = 0 to 16 m/s at t = 6.0 s. What distance does the car travel during these 6.0 s?

  1. 120 m
  2. 96 m
  3. 30 m
  4. 60 m Correct answer.

Explanation

The distance travelled is the area under the velocity–time graph. For a straight line from 4.0 m/s to 16 m/s over 6.0 s, the area is the average velocity × time = (4.0 + 16)/2 × 6.0 = 60 m. Equivalently, it is the area of the trapezium under the line.