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CAPE Physics Unit 1 study materials
CAPE Physics Unit 1 study resources

CAPE Physics Unit 1 practice questions

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Question 1Mechanics

Which of the following is an SI base quantity?

  1. Force
  2. Energy
  3. Amount of substance Correct answer.
  4. Velocity

Explanation

The seven SI base quantities are length, mass, time, electric current, thermodynamic temperature, amount of substance and luminous intensity. Amount of substance (unit: mole) is one of them.

Question 2Mechanics

The unit of force, the newton, expressed in SI base units, is:

  1. kg m s^-1
  2. kg m s^-2 Correct answer.
  3. kg m^2 s^-2
  4. kg m^-1 s^-2

Explanation

From F = ma, force has units of mass times acceleration: kg multiplied by m s^-2, giving kg m s^-2. One newton equals 1 kg m s^-2.

Question 3Mechanics

Which pair contains only vector quantities?

  1. Speed and distance
  2. Mass and energy
  3. Displacement and acceleration Correct answer.
  4. Temperature and time

Explanation

Vectors have both magnitude and direction. Displacement and acceleration are both vectors, so this pair is correct.

Question 4Mechanics

A car accelerates uniformly from rest to 20 m s^-1 in 8.0 s. What is its acceleration?

  1. 2.5 m s^-2 Correct answer.
  2. 4.0 m s^-2
  3. 12 m s^-2
  4. 160 m s^-2

Explanation

Acceleration a = (v - u)/t = (20 - 0)/8.0 = 2.5 m s^-2. The change in velocity divided by the time taken gives the uniform acceleration.

Question 5Mechanics

A ball is dropped from rest and falls freely for 3.0 s. Taking g = 9.81 m s^-2 and ignoring air resistance, how far does it fall?

  1. 14.7 m
  2. 29.4 m
  3. 44.1 m Correct answer.
  4. 88.3 m

Explanation

Using s = ut + (1/2)gt^2 with u = 0: s = 0.5 x 9.81 x 3.0^2 = 0.5 x 9.81 x 9.0 = 44.1 m.

Question 6Mechanics

A projectile is launched at 30 m s^-1 at 60 degrees above the horizontal. What is the horizontal component of its initial velocity? (cos 60 = 0.50)

  1. 15 m s^-1 Correct answer.
  2. 26 m s^-1
  3. 30 m s^-1
  4. 60 m s^-1

Explanation

The horizontal component is v cos(theta) = 30 x cos 60 = 30 x 0.50 = 15 m s^-1. The horizontal velocity stays constant during flight when air resistance is ignored.

Question 7Mechanics

For a projectile launched over level ground (ignoring air resistance), at the highest point of its path:

  1. Both velocity components are zero
  2. The vertical velocity is zero but horizontal velocity is not Correct answer.
  3. The horizontal velocity is zero but vertical velocity is not
  4. The acceleration is zero

Explanation

At the top of the trajectory the vertical velocity is momentarily zero, while the horizontal velocity remains unchanged. The acceleration is still g downward throughout the flight.

Question 8Mechanics

Newton's first law of motion states that a body will:

  1. Accelerate in the direction of the net force
  2. Remain at rest or move with constant velocity unless acted on by a net external force Correct answer.
  3. Exert a force equal and opposite to any force on it
  4. Always come to rest because of friction

Explanation

Newton's first law (the law of inertia) states that a body continues at rest or in uniform motion in a straight line unless a resultant external force acts on it.

Question 9Mechanics

Newton's second law in its most general form states that the resultant force on a body equals:

  1. The product of mass and velocity
  2. The rate of change of momentum Correct answer.
  3. The rate of change of kinetic energy
  4. Mass divided by acceleration

Explanation

In its general form, F = dp/dt: the resultant force equals the rate of change of momentum. For constant mass this reduces to F = ma.

Question 10Mechanics

A 2.0 kg trolley moving at 3.0 m s^-1 collides and sticks to a stationary 4.0 kg trolley. What is their common velocity after the collision?

  1. 1.0 m s^-1 Correct answer.
  2. 1.5 m s^-1
  3. 2.0 m s^-1
  4. 3.0 m s^-1

Explanation

By conservation of momentum: (2.0 x 3.0) + 0 = (2.0 + 4.0)v, so 6.0 = 6.0v, giving v = 1.0 m s^-1.

Question 11Mechanics

In a perfectly elastic collision, which quantity is conserved that is NOT conserved in an inelastic collision?

  1. Linear momentum
  2. Total energy
  3. Kinetic energy Correct answer.
  4. Mass

Explanation

Both elastic and inelastic collisions conserve momentum and total energy, but only elastic collisions conserve kinetic energy. In inelastic collisions some kinetic energy is transformed into heat, sound or deformation.

Question 12Mechanics

Impulse is best defined as:

  1. Force divided by time
  2. The change in momentum of a body Correct answer.
  3. The rate of change of velocity
  4. Mass times acceleration

Explanation

Impulse equals force multiplied by the time for which it acts, and by Newton's second law this equals the change in momentum of the body. Its unit is N s, equivalent to kg m s^-1.

Question 13Mechanics

A uniform beam of length 4.0 m rests on a pivot at its centre. A 30 N weight hangs 1.5 m from the pivot on one side. To balance it, what weight must hang 1.0 m from the pivot on the other side?

  1. 20 N
  2. 30 N
  3. 45 N Correct answer.
  4. 60 N

Explanation

For equilibrium, the moments balance: 30 x 1.5 = W x 1.0, so 45 = W, giving W = 45 N.

Question 14Mechanics

For a rigid body in equilibrium under coplanar forces, which two conditions must both be satisfied?

  1. Net force zero and net velocity zero
  2. Net force zero and net moment about any point zero Correct answer.
  3. Net moment zero and net momentum zero
  4. Net force maximum and net moment zero

Explanation

A body is in equilibrium when the vector sum of forces is zero (no translational acceleration) and the sum of moments about any point is zero (no rotational acceleration).

Question 15Mechanics

A force of 50 N moves an object 4.0 m in the direction of the force. How much work is done?

  1. 12.5 J
  2. 46 J
  3. 54 J
  4. 200 J Correct answer.

Explanation

Work done W = Fs cos(theta). Here the force acts along the direction of motion, so W = 50 x 4.0 = 200 J.

Question 16Mechanics

A 1500 W motor lifts a load steadily, doing 9000 J of useful work in 10 s. What is the useful power output, and is the motor working at full rated power?

  1. 900 W; below rated power Correct answer.
  2. 1500 W; exactly at rated power
  3. 9000 W; above rated power
  4. 90 W; below rated power

Explanation

Useful power = work/time = 9000/10 = 900 W. Since 900 W is less than the 1500 W rating, the motor is operating below its rated power (the rest is lost or unused).

Question 17Mechanics

A 0.50 kg ball is thrown vertically and rises to a height of 5.0 m. Taking g = 9.81 m s^-2, what is its gain in gravitational potential energy?

  1. 2.5 J
  2. 9.8 J
  3. 24.5 J Correct answer.
  4. 49 J

Explanation

Gain in PE = mgh = 0.50 x 9.81 x 5.0 = 24.5 J. The potential energy increases as the ball gains height.

Question 18Mechanics

An object of mass 2.0 kg moves at 6.0 m s^-1. What is its kinetic energy?

  1. 6.0 J
  2. 12 J
  3. 36 J Correct answer.
  4. 72 J

Explanation

Kinetic energy = (1/2)mv^2 = 0.5 x 2.0 x 6.0^2 = 0.5 x 2.0 x 36 = 36 J.

Question 19Mechanics

An object moves in a circle of radius 2.0 m with a constant speed of 4.0 m s^-1. What is the magnitude of its centripetal acceleration?

  1. 2.0 m s^-2
  2. 4.0 m s^-2
  3. 8.0 m s^-2 Correct answer.
  4. 16 m s^-2

Explanation

Centripetal acceleration a = v^2/r = 4.0^2/2.0 = 16/2.0 = 8.0 m s^-2, directed toward the centre of the circle.

Question 20Mechanics

For an object moving in a horizontal circle at constant speed, the centripetal force is directed:

  1. Along the direction of motion
  2. Outward, away from the centre
  3. Toward the centre of the circle Correct answer.
  4. Vertically downward

Explanation

The centripetal force always points toward the centre of the circular path, continually changing the direction of velocity while keeping the speed constant.

Question 21Mechanics

Newton's law of universal gravitation states that the gravitational force between two point masses is:

  1. Directly proportional to the square of the distance between them
  2. Inversely proportional to the product of their masses
  3. Inversely proportional to the square of the distance between them Correct answer.
  4. Independent of the distance between them

Explanation

The force is given by F = Gm1m2/r^2, so it is directly proportional to the product of the masses and inversely proportional to the square of the separation r.

Question 22Mechanics

A measurement of length is recorded as 2.50 m with an absolute uncertainty of 0.05 m. What is the percentage uncertainty?

  1. 0.5%
  2. 2.0% Correct answer.
  3. 5.0%
  4. 20%

Explanation

Percentage uncertainty = (absolute uncertainty / value) x 100 = (0.05/2.50) x 100 = 2.0%.

Question 23Mechanics

A stone is thrown vertically upward at 14.7 m s^-1. Taking g = 9.81 m s^-2, what is the maximum height reached (ignoring air resistance)?

  1. 7.5 m
  2. 11.0 m Correct answer.
  3. 22.0 m
  4. 44.1 m

Explanation

Using v^2 = u^2 - 2gs with v = 0 at the top: 0 = 14.7^2 - 2(9.81)s, so s = 216.1/19.62 = 11.0 m.

Question 24Mechanics

A 70 kg skydiver reaches terminal velocity. At that moment, the air resistance acting on her is closest to: (g = 9.81 m s^-2)

  1. 0 N
  2. 70 N
  3. 687 N Correct answer.
  4. 1374 N

Explanation

At terminal velocity the net force is zero, so air resistance equals weight: W = mg = 70 x 9.81 = 687 N upward.

Question 25Mechanics

Which graph feature represents the instantaneous velocity of an object on a displacement-time graph?

  1. The area under the graph
  2. The gradient (slope) of the tangent to the curve Correct answer.
  3. The vertical intercept
  4. The horizontal intercept

Explanation

On a displacement-time graph the gradient of the tangent at a point gives the instantaneous velocity, since velocity is the rate of change of displacement.

Question 26Mechanics

On a velocity-time graph, the area between the line and the time axis represents:

  1. Acceleration
  2. Displacement Correct answer.
  3. Momentum
  4. Force

Explanation

The area under a velocity-time graph equals displacement, because displacement is the integral of velocity with respect to time.

Question 27Mechanics

Two forces of 6.0 N and 8.0 N act at right angles to each other at a point. What is the magnitude of their resultant?

  1. 2.0 N
  2. 10 N Correct answer.
  3. 14 N
  4. 48 N

Explanation

For perpendicular forces the resultant is found using Pythagoras: R = square root of (6.0^2 + 8.0^2) = square root of (36 + 64) = square root of 100 = 10 N.

Question 28Mechanics

A box of weight 200 N rests on a slope inclined at 30 degrees to the horizontal. The component of the weight acting down the slope is: (sin 30 = 0.50)

  1. 50 N
  2. 100 N Correct answer.
  3. 173 N
  4. 200 N

Explanation

The component of weight along the slope is W sin(theta) = 200 x sin 30 = 200 x 0.50 = 100 N.

Question 29Mechanics

A rocket expels exhaust gases backward. The forward thrust on the rocket is best explained by:

  1. Newton's first law
  2. Newton's third law Correct answer.
  3. The principle of moments
  4. Hooke's law

Explanation

Newton's third law states that for every action there is an equal and opposite reaction. The rocket pushes gas backward, and the gas pushes the rocket forward with an equal force.

Question 30Mechanics

A car of mass 1000 kg travelling at 20 m s^-1 is brought to rest in 5.0 s by a constant braking force. What is the magnitude of the braking force?

  1. 400 N
  2. 1000 N
  3. 4000 N Correct answer.
  4. 20000 N

Explanation

Deceleration a = (0 - 20)/5.0 = -4.0 m s^-2, so the magnitude of the force is F = ma = 1000 x 4.0 = 4000 N.

Question 31Mechanics

The principle of conservation of linear momentum applies to a system provided that:

  1. No external resultant force acts on the system Correct answer.
  2. The collision is perfectly elastic
  3. The bodies have equal mass
  4. Kinetic energy is conserved

Explanation

Linear momentum is conserved whenever no external resultant force acts on the system. This holds for both elastic and inelastic collisions and regardless of the masses involved.

Question 32Mechanics

An object weighs 60 N on the surface of the Earth. On a planet where the gravitational field strength is one third that of Earth, its weight would be:

  1. 20 N Correct answer.
  2. 60 N
  3. 180 N
  4. 0 N

Explanation

Weight equals mass times gravitational field strength. The mass is unchanged, so with g reduced to one third, the weight becomes 60/3 = 20 N.

Question 33Mechanics

A 5.0 kg object is raised vertically at constant speed through 8.0 m. Taking g = 9.81 m s^-2, the work done against gravity is:

  1. 40 J
  2. 49 J
  3. 392 J Correct answer.
  4. 785 J

Explanation

Work done against gravity equals the gain in potential energy: W = mgh = 5.0 x 9.81 x 8.0 = 392 J.

Question 34Mechanics

A couple consists of two forces that are:

  1. Equal, parallel and act in the same direction
  2. Equal, parallel, opposite in direction and not along the same line Correct answer.
  3. Unequal and perpendicular
  4. Equal and acting along the same line

Explanation

A couple is a pair of equal, parallel forces acting in opposite directions but not along the same line. It produces a turning effect (torque) but no resultant linear force.

Question 35Mechanics

A uniform metre rule is pivoted at its centre. A 2.0 N weight hangs at the 20 cm mark. At what mark must a 4.0 N weight hang to balance the rule?

  1. 60 cm
  2. 65 cm Correct answer.
  3. 70 cm
  4. 80 cm

Explanation

The pivot is at 50 cm. The 2.0 N weight is 30 cm from the pivot, giving a moment of 60 N cm. For balance, 4.0 N x d = 60, so d = 15 cm from the pivot, i.e. at the 65 cm mark.

Question 36Mechanics

Which of the following has the same SI base units as energy?

  1. Power
  2. Work Correct answer.
  3. Force
  4. Momentum

Explanation

Work and energy share the same unit, the joule (kg m^2 s^-2), because work done is a transfer of energy.

Question 37Mechanics

A car travels 120 m east then 50 m north. What is the magnitude of its displacement from the start?

  1. 70 m
  2. 130 m Correct answer.
  3. 170 m
  4. 6000 m

Explanation

Displacement is the straight-line distance: magnitude = square root of (120^2 + 50^2) = square root of (14400 + 2500) = square root of 16900 = 130 m.

Question 38Waves Optics

A body undergoes simple harmonic motion when its acceleration is:

  1. Constant in magnitude and direction
  2. Proportional to displacement and directed away from equilibrium
  3. Proportional to displacement and directed toward equilibrium Correct answer.
  4. Inversely proportional to displacement

Explanation

The defining condition for SHM is a = -(omega^2)x: the acceleration is proportional to the displacement from equilibrium and always directed back toward equilibrium (the restoring nature gives the minus sign).

Question 39Waves Optics

An object in simple harmonic motion has its maximum speed:

  1. At the extremes of its motion
  2. At the equilibrium position Correct answer.
  3. Midway between equilibrium and the amplitude
  4. At all points equally

Explanation

In SHM the speed is greatest at the equilibrium position, where displacement is zero, and is zero at the amplitude extremes where the object momentarily stops to reverse direction.

Question 40Waves Optics

For a simple pendulum undergoing small oscillations, the period depends on:

  1. The mass of the bob
  2. The amplitude of swing
  3. The length of the pendulum and g Correct answer.
  4. The colour of the bob

Explanation

For small angles, T = 2 pi square root of (L/g). The period depends only on the length L and the acceleration due to gravity g, not on the mass or (for small swings) the amplitude.

Question 41Waves Optics

During simple harmonic motion, when the displacement is maximum, the energy of the system is:

  1. Entirely kinetic
  2. Entirely potential Correct answer.
  3. Equally kinetic and potential
  4. Zero

Explanation

At maximum displacement the object is momentarily at rest, so kinetic energy is zero and all the energy is potential. The total energy stays constant throughout the motion.

Question 42Waves Optics

Light damping of an oscillating system causes the:

  1. Frequency to increase steadily
  2. Amplitude to decrease gradually over time Correct answer.
  3. Period to become zero
  4. Energy to increase over time

Explanation

Damping removes energy from an oscillating system, so the amplitude decreases gradually. With light damping the system still oscillates but the swings get smaller over time.

Question 43Waves Optics

Resonance occurs when a system is driven at a frequency:

  1. Much higher than its natural frequency
  2. Much lower than its natural frequency
  3. Equal to its natural frequency Correct answer.
  4. Equal to zero

Explanation

Resonance occurs when the driving frequency equals (or is very close to) the natural frequency of the system, producing a large amplitude response as energy is transferred most efficiently.

Question 44Waves Optics

A wave has a frequency of 50 Hz and a wavelength of 6.0 m. What is its speed?

  1. 8.3 m s^-1
  2. 44 m s^-1
  3. 300 m s^-1 Correct answer.
  4. 56 m s^-1

Explanation

Using the wave equation v = f lambda = 50 x 6.0 = 300 m s^-1.

Question 45Waves Optics

In a transverse wave, the oscillations of the particles are:

  1. Parallel to the direction of energy travel
  2. Perpendicular to the direction of energy travel Correct answer.
  3. In circles about a fixed point
  4. Absent, since particles do not move

Explanation

In a transverse wave the particle oscillations are at right angles to the direction in which the wave (and its energy) travels. Examples include light and waves on a string.

Question 46Waves Optics

Which of the following is a longitudinal wave?

  1. Light wave
  2. Sound wave in air Correct answer.
  3. Water surface ripple
  4. Wave on a stretched string

Explanation

A sound wave in air is longitudinal: the air particles oscillate back and forth parallel to the direction the wave travels, creating compressions and rarefactions.

Question 47Waves Optics

Two coherent sources produce an interference pattern. A point of constructive interference occurs where the path difference is:

  1. A whole number of wavelengths Correct answer.
  2. An odd number of half wavelengths
  3. One quarter of a wavelength
  4. Always zero

Explanation

Constructive interference occurs where the waves arrive in phase, which happens when the path difference is a whole number of wavelengths (0, lambda, 2 lambda, and so on).

Question 48Waves Optics

A stationary (standing) wave is formed by the superposition of two waves that are:

  1. Of different frequencies travelling in the same direction
  2. Of equal frequency and amplitude travelling in opposite directions Correct answer.
  3. Of equal frequency travelling in the same direction
  4. Of different speeds in the same medium

Explanation

A stationary wave results when two waves of equal frequency, wavelength and amplitude travel in opposite directions and superpose, producing fixed nodes and antinodes.

Question 49Waves Optics

On a stationary wave, the distance between two adjacent nodes is equal to:

  1. One wavelength
  2. Half a wavelength Correct answer.
  3. One quarter of a wavelength
  4. Two wavelengths

Explanation

On a stationary wave, adjacent nodes (or adjacent antinodes) are separated by half a wavelength. A node and the next antinode are a quarter wavelength apart.

Question 50Waves Optics

Polarisation can occur for:

  1. Sound waves only
  2. Both transverse and longitudinal waves
  3. Transverse waves only Correct answer.
  4. Longitudinal waves only

Explanation

Only transverse waves can be polarised, because polarisation restricts oscillations to a single plane perpendicular to the direction of travel. Longitudinal waves cannot be polarised since their oscillations are along the travel direction.