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Fukuoka Entrance Science study materials
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Fukuoka Entrance Science practice questions

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Question 1Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A ball is thrown straight up and later returns to the thrower's hand. Ignoring air resistance, what is the acceleration of the ball at the highest point of its path?

  1. It depends on the initial speed
  2. 0 m/s²
  3. 9.8 m/s² downward Correct answer.
  4. 9.8 m/s² upward

Explanation

Gravity acts on the ball at every instant of the flight, including the top of the path where the velocity is momentarily zero. The acceleration is therefore the gravitational acceleration, about 9.8 m/s² directed downward. Only the velocity becomes zero at the top; the acceleration never does.

Question 2Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A car travelling at 20 m/s brakes and stops in 4.0 s with constant deceleration. What distance does it travel while stopping?

  1. 40 m Correct answer.
  2. 80 m
  3. 20 m
  4. 100 m

Explanation

For constant acceleration the average velocity during braking is the mean of the initial and final velocities, (20 + 0)/2 = 10 m/s. Multiplying by the stopping time gives 10 m/s × 4.0 s = 40 m. Equivalently, use s = ut + ½at² with a = −5 m/s².

Question 3Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A box is pushed across a rough floor at constant velocity by a horizontal force of 30 N. What is the magnitude of the kinetic friction force acting on the box?

  1. Greater than 30 N
  2. Less than 30 N but not zero
  3. 0 N
  4. 30 N Correct answer.

Explanation

Constant velocity means the net horizontal force is zero, so the pushing force and kinetic friction must balance exactly. Therefore the friction magnitude equals the applied force, 30 N. The forces are equal in size and opposite in direction.

Question 4Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Two forces act on a small object: 6 N to the east and 8 N to the north. What is the magnitude of the resultant force?

  1. 2 N
  2. 48 N
  3. 14 N
  4. 10 N Correct answer.

Explanation

The two forces are perpendicular, so the resultant is found with the Pythagorean theorem: √(6² + 8²) = √100 = 10 N. Adding magnitudes directly is only valid when the forces point along the same line. The direction of the resultant lies between east and north.

Question 5Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 2.0 kg object is lifted vertically at constant speed through a height of 3.0 m. Taking g = 9.8 m/s², how much gravitational potential energy does it gain?

  1. 59 J Correct answer.
  2. 120 J
  3. 20 J
  4. 6.0 J

Explanation

Gain in gravitational potential energy equals mgh = 2.0 kg × 9.8 m/s² × 3.0 m ≈ 59 J. Because the object moves at constant speed, the lifting force does exactly this much work. The result does not depend on how fast the lift is performed.

Question 6Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A pendulum swings back and forth. At which position is its kinetic energy greatest?

  1. At the lowest point of the swing Correct answer.
  2. Kinetic energy is the same everywhere
  3. At the highest point of the swing
  4. Halfway between the highest and lowest points

Explanation

As the pendulum falls toward the lowest point, gravitational potential energy is converted into kinetic energy, so speed and kinetic energy are maximum at the bottom. At the highest points the pendulum momentarily stops, so all energy is potential. Total mechanical energy stays constant if air resistance is neglected.

Question 7Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A current of 2.0 A flows through a resistor of 15 Ω. What is the potential difference across the resistor?

  1. 7.5 V
  2. 30 V Correct answer.
  3. 0.13 V
  4. 17 V

Explanation

Ohm's law states V = IR, so V = 2.0 A × 15 Ω = 30 V. The voltage is the product of current and resistance. Dividing instead of multiplying gives an incorrect result.

Question 8Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Which statement correctly describes the direction of the magnetic field around a long straight wire carrying a current?

  1. The field lines point radially inward toward the wire
  2. The field lines point radially outward from the wire
  3. The field lines run parallel to the wire
  4. The field lines form circles centred on the wire Correct answer.

Explanation

A current-carrying straight wire produces a magnetic field whose lines are concentric circles around the wire, with the direction given by the right-hand grip rule. The field is not radial and is not parallel to the current. Its strength decreases with distance from the wire.

Question 9Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A wave has a frequency of 50 Hz and a wavelength of 4.0 m. What is its speed?

  1. 54 m/s
  2. 200 m/s Correct answer.
  3. 12.5 m/s
  4. 0.08 m/s

Explanation

The wave equation gives v = fλ, so v = 50 Hz × 4.0 m = 200 m/s. Frequency is the number of cycles per second and wavelength is the length of one cycle, so their product is the distance travelled per second.

Question 10Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A sound wave travels from air into water. Which quantity remains unchanged as it crosses the boundary?

  1. Speed
  2. Frequency Correct answer.
  3. Wavelength
  4. Direction of propagation

Explanation

Frequency is set by the source and does not change when a wave enters a new medium. Because the speed of sound is greater in water than in air, the wavelength must increase to keep fλ equal to the new speed. The direction also changes by refraction.

Question 11Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A student stands 170 m from a cliff and claps. She hears the echo 1.0 s later. Using this data, what is the speed of sound in the air?

  1. 170 m/s
  2. 85 m/s
  3. 340 m/s Correct answer.
  4. 680 m/s

Explanation

The sound must travel to the cliff and back, a total distance of 2 × 170 m = 340 m, in 1.0 s. Dividing total distance by time gives 340 m/s. Forgetting the return trip is the most common error.

Question 12Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A ray of light strikes a plane mirror at an angle of 30° to the mirror surface. What is the angle between the reflected ray and the normal?

  1. 30°
  2. 0°
  3. 90°
  4. 60° Correct answer.

Explanation

Angles in reflection are measured from the normal, not from the surface. If the incident ray makes 30° with the mirror, it makes 90° − 30° = 60° with the normal, and the reflected ray makes the same 60° with the normal. The law of reflection states the angle of incidence equals the angle of reflection.

Question 13Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

An object is placed 30 cm from a converging lens of focal length 10 cm. Where is the image formed?

  1. 15 cm on the opposite side of the lens Correct answer.
  2. 7.5 cm on the opposite side of the lens
  3. 30 cm on the same side as the object
  4. 10 cm on the opposite side of the lens

Explanation

Using the thin-lens equation 1/f = 1/u + 1/v with f = 10 cm and u = 30 cm gives 1/v = 1/10 − 1/30 = 2/30, so v = 15 cm. A positive image distance means a real image on the far side of the lens. The image is also inverted and diminished.

Question 14Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

White light passes through a glass prism and spreads into a spectrum. What causes this dispersion?

  1. The refractive index of glass differs for different wavelengths Correct answer.
  2. The prism absorbs some colours completely
  3. The colours have different frequencies after leaving the prism
  4. All colours travel at the same speed in glass but reflect differently

Explanation

Glass has a slightly different refractive index for each wavelength, so each colour is refracted by a different amount. This difference in bending separates white light into its component colours. The frequency of each colour is unchanged by the prism.

Question 15Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Two identical resistors of 6 Ω are connected in parallel. What is the total resistance of the combination?

  1. 3 Ω Correct answer.
  2. 6 Ω
  3. 12 Ω
  4. 1.5 Ω

Explanation

For two equal resistors in parallel the total resistance is half of one resistor, so 6 Ω / 2 = 3 Ω. Formally, 1/R = 1/6 + 1/6 = 2/6, giving R = 3 Ω. The parallel combination is always smaller than the smallest individual resistor.

Question 16Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 12 V battery is connected to a 4 Ω resistor. How much electrical power is dissipated in the resistor?

  1. 0.33 W
  2. 48 W
  3. 36 W Correct answer.
  4. 3 W

Explanation

Power can be calculated as P = V²/R = (12)²/4 = 144/4 = 36 W. Equivalently, the current is 3 A and P = VI = 12 × 3 = 36 W. Both routes give the same result.

Question 17Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A charged particle moves horizontally to the right through a uniform magnetic field directed into the page. In which direction is the magnetic force on a positively charged particle?

  1. To the left
  2. Upward Correct answer.
  3. Downward
  4. Into the page

Explanation

The magnetic force is given by F = qv × B. With velocity to the right and field into the page, the cross product points upward for a positive charge, as given by Fleming's left-hand rule or the right-hand rule. The force is perpendicular to both velocity and field.

Question 18Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A spring obeys Hooke's law with a spring constant of 200 N/m. How much force is needed to stretch it by 0.10 m?

  1. 20 N Correct answer.
  2. 2000 N
  3. 0.0005 N
  4. 2 N

Explanation

Hooke's law gives F = kx = 200 N/m × 0.10 m = 20 N. The force is proportional to the extension for a linear spring. Doubling the extension would double the required force.

Question 19Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A block slides down a frictionless inclined plane. Which statement about its acceleration along the slope is correct?

  1. It is zero because the block moves at constant speed
  2. It equals g, independent of the angle
  3. It equals g cos θ
  4. It equals g sin θ, where θ is the angle of the incline Correct answer.

Explanation

The component of gravity along the slope is mg sin θ, so the acceleration along the slope is g sin θ. As the incline becomes steeper, sin θ approaches 1 and the acceleration approaches g. The normal force balances the perpendicular component mg cos θ.

Question 20Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A wave has a period of 0.25 s. What is its frequency?

  1. 2.5 Hz
  2. 4 Hz Correct answer.
  3. 25 Hz
  4. 0.25 Hz

Explanation

Frequency is the reciprocal of the period: f = 1/T = 1/0.25 s = 4 Hz. This means four complete cycles occur each second. A shorter period always corresponds to a higher frequency.

Question 21Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

An object is placed 20 cm in front of a plane mirror. How far is the image from the object?

  1. 10 cm
  2. 40 cm Correct answer.
  3. 20 cm
  4. 0 cm

Explanation

A plane mirror forms a virtual image as far behind the mirror as the object is in front of it. With the object 20 cm in front, the image is 20 cm behind, so the separation between object and image is 20 + 20 = 40 cm. The image is the same size as the object and upright.

Question 22Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A moving car doubles its speed. By what factor does its kinetic energy change, assuming its mass stays the same?

  1. It becomes twice as large
  2. It stays the same
  3. It becomes four times larger Correct answer.
  4. It becomes half as large

Explanation

Kinetic energy is ½mv², so it is proportional to the square of the speed. Doubling v multiplies the kinetic energy by 2² = 4. This is why braking distance grows much faster than speed.

Question 23Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 0.50 kg ball moving at 4.0 m/s collides head-on with a stationary 0.50 kg ball and they stick together. What is their common velocity just after the collision?

  1. 1.0 m/s
  2. 2.0 m/s Correct answer.
  3. 0 m/s
  4. 4.0 m/s

Explanation

Momentum is conserved in the collision: 0.50 × 4.0 = (0.50 + 0.50) × v, so v = 2.0/1.0 = 2.0 m/s. The combined mass is twice the original, so the velocity is halved. Kinetic energy is not conserved because the collision is inelastic.

Question 24Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Which of the following correctly describes how a step-up transformer changes voltage and current?

  1. It increases both voltage and current
  2. It increases voltage and decreases current Correct answer.
  3. It decreases voltage and increases current
  4. It increases voltage without changing current

Explanation

A step-up transformer has more turns on the secondary coil, raising the voltage. Because ideal transformers conserve power, an increase in voltage must be accompanied by a proportional decrease in current. The product VI stays approximately constant.

Question 25Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Two tuning forks are sounded together and a beat frequency of 3 Hz is heard. One fork is known to vibrate at 440 Hz. Which pair of frequencies could the other fork have?

  1. 437 Hz only
  2. 443 Hz only
  3. 440 Hz only
  4. 443 Hz or 437 Hz Correct answer.

Explanation

Beats occur at the difference between the two frequencies, so the unknown fork could be 440 + 3 = 443 Hz or 440 − 3 = 437 Hz. Without further information both values are possible. The beat frequency tells you the size of the difference, not its sign.

Question 26Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A box is pushed across a horizontal floor at constant velocity by a horizontal force of 20 N. What is the magnitude of the friction force acting on the box?

  1. 20 N Correct answer.
  2. 0 N
  3. 40 N
  4. 10 N

Explanation

Constant velocity means the net force is zero, so the friction force must exactly balance the applied force. Since the applied force is 20 N horizontally, friction is also 20 N in the opposite direction.

Question 27Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 2.0 kg object is lifted vertically upward at a steady speed of 0.50 m/s. Taking g = 10 m/s², at what rate is work being done against gravity?

  1. 1.0 W
  2. 5.0 W
  3. 10 W Correct answer.
  4. 20 W

Explanation

Power equals force times velocity. The lifting force must equal the weight, mg = 2.0 × 10 = 20 N, so power = 20 N × 0.50 m/s = 10 W.

Question 28Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

An electric heater carries a current of 5.0 A when connected to a 100 V supply. What is the resistance of its heating element?

  1. 20 Ω Correct answer.
  2. 0.050 Ω
  3. 500 Ω
  4. 105 Ω

Explanation

Ohm's law gives R = V/I. Substituting V = 100 V and I = 5.0 A gives R = 100/5.0 = 20 Ω.

Question 29Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Which property of a sound wave determines its pitch as heard by a listener?

  1. Its frequency Correct answer.
  2. Its amplitude
  3. Its waveform shape
  4. Its speed in air

Explanation

Pitch corresponds to how rapidly the air pressure oscillates, which is the frequency of the sound wave. Higher frequency gives a higher perceived pitch.

Question 30Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A converging lens is used as a magnifying glass. Where must the object be placed to produce an upright, virtual, magnified image?

  1. Between one and two focal lengths from the lens
  2. Closer to the lens than its focal length Correct answer.
  3. Beyond twice the focal length
  4. Exactly at the focal point

Explanation

When the object lies inside the focal length of a converging lens, the rays diverge after refraction and form an upright virtual image on the same side. This is the arrangement used for a magnifying glass.

Question 31Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A straight wire carrying a current is placed in a uniform magnetic field so that the wire is parallel to the field lines. What is the magnitude of the magnetic force on the wire?

  1. Maximum possible for that current and field
  2. Zero Correct answer.
  3. Equal to the field strength times the wire length
  4. Equal to the current times the field strength

Explanation

The magnetic force on a current-carrying wire is F = BIL sin θ, where θ is the angle between the wire and the field. When the wire is parallel to the field, θ = 0 and sin θ = 0, so the force vanishes.

Question 32Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A car travels 150 m in 10 s while moving at a constant speed. What is its speed?

  1. 1500 m/s
  2. 15 m/s Correct answer.
  3. 150 m/s
  4. 1.5 m/s

Explanation

For constant speed, speed equals distance divided by time. Dividing 150 m by 10 s gives 15 m/s.

Question 33Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Two point charges are separated by a certain distance. If the distance between them is doubled while the charges stay the same, how does the electric force between them change?

  1. It becomes twice as large
  2. It becomes one quarter as large Correct answer.
  3. It becomes one half as large
  4. It becomes four times as large

Explanation

Coulomb's law states that the force is inversely proportional to the square of the separation. Doubling the distance multiplies the force by 1/2² = 1/4, so it becomes one quarter as large.

Question 34Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A cyclist accelerates uniformly from rest to 8.0 m/s in 4.0 s. What distance does she cover during this time?

  1. 8.0 m
  2. 32 m
  3. 16 m Correct answer.
  4. 64 m

Explanation

With uniform acceleration from rest, average velocity is (0 + 8.0)/2 = 4.0 m/s. Distance is average velocity times time: 4.0 × 4.0 = 16 m.

Question 35Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 3.0 kg object moving at 4.0 m/s collides with a stationary 1.0 kg object, and they move off together. What is their common velocity after the collision?

  1. 12 m/s
  2. 1.0 m/s
  3. 3.0 m/s Correct answer.
  4. 4.0 m/s

Explanation

Momentum is conserved: (3.0)(4.0) + 0 = (3.0 + 1.0)v. This gives 12 = 4.0v, so v = 3.0 m/s.

Question 36Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 60 W lamp is switched on for 5.0 minutes. How much electrical energy does it transfer?

  1. 3.0 × 10⁴ J
  2. 3.0 × 10² J
  3. 1.8 × 10⁴ J Correct answer.
  4. 1.8 × 10² J

Explanation

Energy equals power times time, with time in seconds: 5.0 min = 300 s. Then E = 60 W × 300 s = 18 000 J = 1.8 × 10⁴ J.

Question 37Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 4.0 Ω resistor and a 12 Ω resistor are connected in series across a 16 V supply. What is the potential difference across the 4.0 Ω resistor?

  1. 16 V
  2. 1.0 V
  3. 4.0 V Correct answer.
  4. 12 V

Explanation

The total resistance is 16 Ω, so the current is 16 V / 16 Ω = 1.0 A. The voltage across the 4.0 Ω resistor is 1.0 A × 4.0 Ω = 4.0 V.

Question 38Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A transverse wave on a string has an amplitude of 0.20 m and a wavelength of 1.5 m. What is the vertical distance between a crest and the adjacent trough?

  1. 0.40 m Correct answer.
  2. 0.20 m
  3. 0.75 m
  4. 1.5 m

Explanation

The crest is one amplitude above the equilibrium line and the trough is one amplitude below it. The distance between them is twice the amplitude, 2 × 0.20 = 0.40 m.

Question 39Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Light travelling in air strikes the flat surface of a glass block at an angle of incidence of 40°. Which statement about the refracted ray is correct?

  1. It is totally internally reflected because the angle is above the critical angle
  2. It bends toward the normal because light travels more slowly in glass Correct answer.
  3. It continues in a straight line because the frequency is unchanged
  4. It bends away from the normal because glass is denser

Explanation

Glass has a higher refractive index than air, so light slows down on entering it. By Snell's law the ray bends toward the normal, giving an angle of refraction smaller than 40°.

Question 40Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A concave mirror has a focal length of 10 cm. An object is placed 15 cm in front of it. Where is the image formed?

  1. 6.0 cm in front of the mirror
  2. 15 cm behind the mirror
  3. 30 cm behind the mirror
  4. 30 cm in front of the mirror Correct answer.

Explanation

Using 1/f = 1/u + 1/v with f = 10 cm and u = 15 cm gives 1/v = 1/10 − 1/15 = 1/30, so v = 30 cm. A positive image distance for a concave mirror means a real image in front of the mirror.

Question 41Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A step-down transformer has 1000 turns on its primary coil and 50 turns on its secondary. If the primary is supplied with 200 V, what is the secondary voltage?

  1. 10 V Correct answer.
  2. 4.0 V
  3. 100 V
  4. 4000 V

Explanation

For an ideal transformer the voltage ratio equals the turns ratio: Vs/Vp = Ns/Np. Thus Vs = 200 × 50/1000 = 10 V.

Question 42Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A spring of spring constant 400 N/m is compressed by 0.050 m. How much elastic potential energy is stored?

  1. 20 J
  2. 0.50 J Correct answer.
  3. 1.0 J
  4. 0.025 J

Explanation

Elastic potential energy is E = ½kx². Substituting k = 400 N/m and x = 0.050 m gives ½ × 400 × 0.0025 = 0.50 J.

Question 43Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

An object floats with 60% of its volume submerged in a liquid. What is the density of the object if the liquid has a density of 1000 kg/m³?

  1. 1000 kg/m³
  2. 1670 kg/m³
  3. 400 kg/m³
  4. 600 kg/m³ Correct answer.

Explanation

For a floating body, the fraction submerged equals the ratio of object density to liquid density. Thus the object density is 0.60 × 1000 = 600 kg/m³.

Question 44Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A sound source moves toward a stationary observer. Compared with the sound emitted when the source is at rest, how does the observed sound change?

  1. Lower frequency and longer wavelength
  2. Higher frequency and longer wavelength
  3. Higher frequency and shorter wavelength Correct answer.
  4. Same frequency and higher amplitude

Explanation

As the source approaches, successive wavefronts are emitted closer together, so the observed wavelength is shortened. Because the speed of sound in air is fixed, a shorter wavelength corresponds to a higher observed frequency.

Question 45Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 0.10 kg ball is dropped from a height of 5.0 m and bounces back to a height of 3.2 m. Taking g = 10 m/s², what fraction of its mechanical energy is lost in the bounce?

  1. 80%
  2. 36% Correct answer.
  3. 20%
  4. 64%

Explanation

Potential energy is proportional to height, so the energy just before and after the bounce is proportional to 5.0 m and 3.2 m. The retained fraction is 3.2/5.0 = 0.64, so the fraction lost is 1 − 0.64 = 0.36, or 36%.

Question 46Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Three identical resistors, each of resistance R, are connected so that two are in parallel and this pair is in series with the third. What is the total resistance of the network?

  1. 2.5R
  2. 1.5R Correct answer.
  3. 3.0R
  4. 0.67R

Explanation

Two resistors of resistance R in parallel give R/2. Adding the third resistor in series gives R/2 + R = 1.5R.

Question 47Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A charged particle enters a uniform magnetic field with its velocity perpendicular to the field and moves in a circular path. If the particle's speed is doubled while the field stays the same, how do the radius and the period of its path change?

  1. The radius halves and the period halves
  2. The radius doubles and the period doubles
  3. The radius doubles and the period is unchanged Correct answer.
  4. The radius is unchanged and the period doubles

Explanation

The magnetic force provides the centripetal force: qvB = mv²/r, so r = mv/(qB), meaning the radius is proportional to speed and doubles. The period T = 2πm/(qB) does not depend on speed, so it stays the same.

Question 48Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A ray of light in glass (refractive index 1.5) strikes the glass-air boundary. What is the critical angle for total internal reflection, given sin⁻¹(1/1.5) ≈ 42°?

  1. 42° Correct answer.
  2. 90°
  3. 30°
  4. 48°

Explanation

At the critical angle the refracted ray grazes the surface at 90°, so Snell's law gives sin θc = n_air/n_glass = 1/1.5. This yields θc ≈ 42°, above which total internal reflection occurs.

Question 49Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

Two coherent light sources produce an interference pattern on a screen. At a point where the path difference from the two sources is exactly one and a half wavelengths, what is observed?

  1. No interference because the path difference is too small
  2. Constructive interference, giving a bright fringe
  3. Destructive interference, giving a dark fringe Correct answer.
  4. A single bright fringe shifted by half a wavelength

Explanation

A path difference of (n + ½)λ, here 1.5λ, means the waves arrive half a cycle out of step and cancel. This produces destructive interference and a dark fringe.

Question 50Physics: forces and motion, energy, electricity and magnetism, waves and sound, light

A 2.0 kg block hangs from a light string over a frictionless pulley and pulls a 3.0 kg block along a frictionless horizontal table. Taking g = 10 m/s², what is the acceleration of the system?

  1. 4.0 m/s² Correct answer.
  2. 2.0 m/s²
  3. 6.7 m/s²
  4. 10 m/s²

Explanation

The driving force is the hanging weight, 2.0 × 10 = 20 N, and the total mass accelerated is 2.0 + 3.0 = 5.0 kg. Newton's second law gives a = 20/5.0 = 4.0 m/s².