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UEE Physics practice questions

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Question 1Mechanics

A particle moves along a straight line with constant acceleration. Which quantity is necessarily constant during the motion?

  1. The rate of change of position
  2. The product of speed and time
  3. The rate of change of velocity Correct answer.
  4. The square of the speed

Explanation

Constant acceleration means the velocity changes by equal amounts in equal time intervals, so the rate of change of velocity is fixed. Position changes at a varying rate, and speed squared grows linearly with displacement rather than staying constant.

Question 2Mechanics

A ball is thrown vertically upward and returns to the launch point. Ignoring air resistance, how does the time to reach the highest point compare with the time to fall back down?

  1. The two times are equal Correct answer.
  2. The upward time is longer
  3. It depends on the launch speed
  4. The downward time is longer

Explanation

The motion is symmetric under constant gravitational acceleration, so the upward and downward legs take equal times for the same displacement magnitude. Launch speed changes both times together but never their ratio.

Question 3Mechanics

A book rests on a horizontal table. According to Newton's third law, the reaction partner to the gravitational force on the book is which force?

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

Explanation

Third-law pairs act on different bodies and are of the same type, so the reaction to Earth pulling the book is the book pulling the Earth. The normal force is a separate interaction between book and table, not the partner of weight.

Question 4Mechanics

A crate is pushed across a rough floor at constant velocity. What is true of the net force on the crate?

  1. It equals the applied force
  2. It points opposite to the motion
  3. It is zero Correct answer.
  4. It points in the direction of motion

Explanation

Constant velocity means zero acceleration, so by Newton's second law the vector sum of all forces is zero. The applied force is balanced by kinetic friction rather than being the net force.

Question 5Mechanics

Two forces of 3 N and 4 N act at right angles on a point mass. What is the magnitude of their resultant?

  1. 5 N Correct answer.
  2. 1 N
  3. 7 N
  4. 12 N

Explanation

Perpendicular vectors add by the Pythagorean theorem, giving the square root of nine plus sixteen, which is five newtons. Simple addition would only apply if the forces were parallel.

Question 6Mechanics

A body moves in a horizontal circle at constant speed. Which statement about its acceleration is correct?

  1. It is zero because the speed is constant
  2. It is directed away from the centre
  3. It is directed toward the centre of the circle Correct answer.
  4. It is directed tangentially to the circle

Explanation

Although speed is constant, the velocity direction changes continuously, producing centripetal acceleration pointing to the centre. A tangential acceleration would change the speed, which is not happening.

Question 7Mechanics

A force does positive work on a particle. What happens to the particle's kinetic energy if it is the only force acting?

  1. It stays the same
  2. It becomes zero
  3. It decreases
  4. It increases Correct answer.

Explanation

The work-energy theorem states that net work equals the change in kinetic energy, so positive net work increases kinetic energy. If other forces also act, only the net work determines the change.

Question 8Mechanics

A 2 kg object moves at 3 m/s. What is its momentum?

  1. 18 kg m/s
  2. 1.5 kg m/s
  3. 6 kg m/s Correct answer.
  4. 5 kg m/s

Explanation

Momentum is the product of mass and velocity, so two kilograms times three metres per second gives six kilogram metres per second. Dividing mass by velocity or squaring the speed gives unrelated quantities.

Question 9Mechanics

A car accelerates uniformly from rest to 20 m/s in 5 s. What distance does it travel during this interval?

  1. 50 m Correct answer.
  2. 200 m
  3. 100 m
  4. 40 m

Explanation

For uniform acceleration from rest, average velocity is half the final velocity, ten metres per second, and multiplying by five seconds gives fifty metres. Using the final velocity throughout would overestimate the distance.

Question 10Mechanics

A projectile is launched at 30 degrees above the horizontal with speed 20 m/s. Taking g as 10 m/s², what is the maximum height reached?

  1. 5 m Correct answer.
  2. 20 m
  3. 15 m
  4. 10 m

Explanation

The vertical component is twenty times sine thirty, which is ten metres per second. Maximum height equals that component squared divided by twice g, giving one hundred over twenty, or five metres.

Question 11Mechanics

A block of mass 5 kg is pulled along a frictionless surface by a horizontal force of 15 N. What is its acceleration?

  1. 3 m/s² Correct answer.
  2. 0.33 m/s²
  3. 20 m/s²
  4. 75 m/s²

Explanation

Newton's second law gives acceleration as force divided by mass, so fifteen newtons divided by five kilograms is three metres per second squared. The frictionless surface means no other horizontal force needs to be subtracted.

Question 12Mechanics

A 4 kg block on a rough horizontal surface experiences a kinetic friction force of 8 N while being pushed. Taking g as 10 m/s², what is the coefficient of kinetic friction?

  1. 0.1
  2. 0.2 Correct answer.
  3. 0.5
  4. 2.0

Explanation

The normal force equals the weight, forty newtons, and the friction coefficient is friction divided by normal force, giving eight over forty, or 0.2. The coefficient is dimensionless and must be less than one for this pair.

Question 13Mechanics

A 2 kg mass moving at 6 m/s collides head-on with a stationary 4 kg mass and they stick together. What is the common velocity after the collision?

  1. 3 m/s
  2. 2 m/s Correct answer.
  3. 1 m/s
  4. 4 m/s

Explanation

Momentum is conserved in a perfectly inelastic collision, so twelve kilogram metres per second is shared by the combined six kilograms, giving two metres per second. Kinetic energy is not conserved here, so it cannot be used to find the velocity.

Question 14Mechanics

A spring of stiffness 200 N/m is compressed by 0.1 m. How much elastic potential energy is stored?

  1. 20 J
  2. 2 J
  3. 1 J Correct answer.
  4. 10 J

Explanation

Elastic potential energy is one half times stiffness times compression squared, giving half of two hundred times 0.01, which is one joule. Forgetting the factor of one half doubles the result.

Question 15Mechanics

A satellite orbits Earth in a circular orbit. If the orbital radius is increased while the orbit remains circular, how does the orbital speed change?

  1. It decreases Correct answer.
  2. It becomes zero
  3. It increases
  4. It stays the same

Explanation

Gravitational attraction provides the centripetal force, giving speed proportional to the inverse square root of radius. A larger radius therefore means a smaller orbital speed, as seen with the slower outer planets.

Question 16Mechanics

A wheel of radius 0.5 m rolls without slipping and its centre moves at 4 m/s. What is its angular velocity?

  1. 8 rad/s Correct answer.
  2. 4 rad/s
  3. 16 rad/s
  4. 2 rad/s

Explanation

Rolling without slipping links linear and angular speed by the radius, so angular velocity is linear speed divided by radius, four over 0.5, giving eight radians per second. Multiplying instead of dividing gives the wrong scale.

Question 17Mechanics

A uniform metre rule is pivoted at its centre and a 2 N weight hangs 30 cm to the left. Where must a 3 N weight be placed on the right to balance it?

  1. 45 cm from the pivot
  2. 30 cm from the pivot
  3. 20 cm from the pivot Correct answer.
  4. 15 cm from the pivot

Explanation

For rotational equilibrium the clockwise and anticlockwise moments must be equal, so two newtons times thirty centimetres equals three newtons times the unknown distance. Solving gives twenty centimetres, closer to the pivot because the weight is larger.

Question 18Mechanics

An object of mass 3 kg is lifted vertically at constant speed through 2 m. Taking g as 10 m/s², how much work is done against gravity?

  1. 60 J Correct answer.
  2. 6 J
  3. 20 J
  4. 30 J

Explanation

Work against gravity equals weight times vertical displacement, so thirty newtons times two metres gives sixty joules. Constant speed means the applied force equals the weight, and no extra kinetic energy is gained.

Question 19Mechanics

A 0.5 kg ball hits a wall horizontally at 10 m/s and rebounds at 8 m/s along the same line. What is the magnitude of the impulse delivered to the ball?

  1. 9 kg m/s Correct answer.
  2. 18 kg m/s
  3. 4 kg m/s
  4. 1 kg m/s

Explanation

Impulse equals the change in momentum, and because the velocity reverses, the change is final minus initial with opposite signs. That gives 0.5 times (8 + 10), which is nine kilogram metres per second.

Question 20Mechanics

A block slides down a frictionless incline of height 5 m starting from rest. Taking g as 10 m/s², what is its speed at the bottom?

  1. 25 m/s
  2. 5 m/s
  3. 10 m/s Correct answer.
  4. 50 m/s

Explanation

Mechanical energy is conserved on a frictionless incline, so the loss of potential energy equals the gain in kinetic energy. This gives speed equal to the square root of twice g h, the square root of one hundred, or ten metres per second.

Question 21Mechanics

Two blocks of masses 3 kg and 1 kg are connected by a light string over a frictionless pulley. Taking g as 10 m/s², what is the acceleration of the system?

  1. 2.5 m/s²
  2. 7.5 m/s²
  3. 10 m/s²
  4. 5 m/s² Correct answer.

Explanation

The net driving force is the weight difference, twenty newtons, and the total mass being accelerated is four kilograms. Dividing gives five metres per second squared, which is less than free fall because both masses move together.

Question 22Mechanics

A particle moves with velocity that changes direction but keeps constant magnitude. Which statement about its acceleration is necessarily true?

  1. It is constant in direction
  2. It is zero
  3. It has a component parallel to the velocity
  4. It has a component perpendicular to the velocity Correct answer.

Explanation

When speed is constant, the tangential component of acceleration is zero, so any nonzero acceleration must be perpendicular to the velocity. This perpendicular component curves the path without changing the speed.

Question 23Mechanics

A solid sphere and a hollow cylinder of equal mass and radius roll without slipping down the same incline from rest. Which reaches the bottom first?

  1. The solid sphere Correct answer.
  2. They arrive together
  3. It depends on the incline angle
  4. The hollow cylinder

Explanation

Rolling acceleration depends on the moment of inertia factor, and the solid sphere has a smaller ratio of inertia to mass times radius squared than the hollow cylinder. The sphere therefore accelerates faster and arrives first, independent of the incline angle.

Question 24Mechanics

A body moves under a single conservative force. Which statement about its total mechanical energy is correct?

  1. It decreases steadily as the body moves
  2. It increases when the force does negative work
  3. It is constant throughout the motion Correct answer.
  4. It equals the kinetic energy at all times

Explanation

For a conservative force, the work done converts between kinetic and potential energy without net loss, so total mechanical energy stays constant. Only non-conservative forces such as friction change the total.

Question 25Mechanics

A particle undergoes simple harmonic motion with amplitude A. At what displacement is its kinetic energy equal to its potential energy?

  1. At x equal to zero
  2. At x equal to A divided by the square root of two Correct answer.
  3. At x equal to A divided by two
  4. At x equal to A

Explanation

Total energy is proportional to A squared, and potential energy is proportional to x squared. Setting potential equal to half the total gives x squared equal to A squared over two, so x is A divided by root two.

Question 26Mechanics

A particle moves along a straight line with displacement given by s = 3t² - 2t + 1, where s is in metres and t in seconds. What is the magnitude of its acceleration?

  1. 2 m/s²
  2. 3 m/s²
  3. 6 m/s² Correct answer.
  4. 4 m/s²

Explanation

Velocity is the first time derivative, v = ds/dt = 6t - 2, and acceleration is the second derivative, a = dv/dt = 6 m/s². The acceleration is constant, so its magnitude is 6 m/s² at every instant.

Question 27Mechanics

A body starts from rest and moves with constant acceleration. After a time T its speed is v. What is the distance it has travelled in that time?

  1. vT/2 Correct answer.
  2. vT
  3. vT/4
  4. 2vT

Explanation

For constant acceleration from rest the average speed is half the final speed, so the distance is (v/2)·T = vT/2. Equivalently, using v = aT and s = ½aT² gives s = ½vT.

Question 28Mechanics

Two forces act at a single point on a particle: 6 N directed east and 8 N directed north. What is the magnitude of the resultant force?

  1. 7 N
  2. 10 N Correct answer.
  3. 14 N
  4. 2 N

Explanation

The two forces are perpendicular, so their resultant is found with Pythagoras: R = √(6² + 8²) = √100 = 10 N. The direction lies between the two forces, at about 53° north of east.

Question 29Mechanics

A block rests on a horizontal table. Which pair of forces forms a Newton's-third-law action–reaction pair?

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

Explanation

An action–reaction pair consists of two forces of the same type, each acting on a different body. The Earth pulls the block down gravitationally, and the block pulls the Earth up gravitationally with equal magnitude.

Question 30Mechanics

A 1200 kg car travelling at 15 m/s brakes and stops in 4 s. What is the magnitude of the average braking force?

  1. 300 N
  2. 1800 N
  3. 4500 N Correct answer.
  4. 7200 N

Explanation

The deceleration is a = Δv/Δt = 15/4 = 3.75 m/s². By Newton's second law the average force is F = ma = 1200 × 3.75 = 4500 N.

Question 31Mechanics

A 0.2 kg ball moving at 5 m/s strikes a wall at right angles and rebounds along the same line at 3 m/s. The contact lasts 0.01 s. What is the magnitude of the average force exerted by the wall on the ball?

  1. 160 N Correct answer.
  2. 40 N
  3. 16 N
  4. 400 N

Explanation

Taking the initial direction as positive, the change in momentum is m(v_final - v_initial) = 0.2(-3 - 5) = -1.6 kg·m/s. The average force is the impulse divided by time: 1.6/0.01 = 160 N.

Question 32Mechanics

A 3 kg block slides on a rough horizontal floor with coefficient of kinetic friction 0.25. Taking g as 10 m/s², what is the friction force on the block?

  1. 7.5 N Correct answer.
  2. 12 N
  3. 30 N
  4. 0.75 N

Explanation

On a horizontal floor the normal force equals the weight, N = mg = 30 N. The kinetic friction is f = μN = 0.25 × 30 = 7.5 N, directed opposite to the sliding.

Question 33Mechanics

A 5 kg object is at rest on a rough plane inclined at 30° to the horizontal, held by friction. Taking g as 10 m/s², what is the minimum coefficient of static friction needed?

  1. 0.50
  2. 0.87
  3. 0.58 Correct answer.
  4. 1.00

Explanation

The component of weight along the plane is mg sin30° = 25 N, and the normal force is mg cos30° ≈ 43.3 N. For equilibrium μ_s must satisfy μ_s ≥ tan30° ≈ 0.58.

Question 34Mechanics

A 2 kg mass moves in a vertical circle of radius 0.5 m at constant speed 4 m/s on the end of a string. Taking g as 10 m/s², what is the tension in the string at the lowest point?

  1. 44 N
  2. 84 N Correct answer.
  3. 20 N
  4. 64 N

Explanation

At the lowest point the tension acts upward and the weight downward, and the net force provides the centripetal force: T - mg = mv²/r. Thus T = mg + mv²/r = 20 + 2(16)/0.5 = 20 + 64 = 84 N.

Question 35Mechanics

A car rounds a flat horizontal curve of radius 50 m. Taking g as 10 m/s² and the coefficient of static friction as 0.4, what is the maximum speed at which it can take the curve without skidding?

  1. 25 m/s
  2. 10 m/s
  3. 14 m/s Correct answer.
  4. 20 m/s

Explanation

Friction supplies the centripetal force, so μmg = mv²/r, giving v = √(μgr) = √(0.4 × 10 × 50) = √200 ≈ 14 m/s.

Question 36Mechanics

A 1500 kg satellite moves in a circular orbit where the gravitational field strength is 8 m/s². What is the gravitational force on the satellite?

  1. 12000 N Correct answer.
  2. 1500 N
  3. 15000 N
  4. 187.5 N

Explanation

The gravitational force on a mass in a field of strength g is F = mg. Here F = 1500 × 8 = 12000 N, directed toward the Earth's centre.

Question 37Mechanics

Two satellites orbit the same planet in circular orbits. Satellite X has four times the orbital radius of satellite Y. What is the ratio of X's orbital period to Y's?

  1. 4
  2. 8 Correct answer.
  3. 16
  4. 2

Explanation

Kepler's third law gives T² ∝ r³, so T ∝ r^(3/2). With r_X/r_Y = 4, the period ratio is 4^(3/2) = 8.

Question 38Mechanics

A 0.5 kg ball moving at 4 m/s collides elastically head-on with a stationary 0.5 kg ball on a frictionless surface. What happens after the collision?

  1. The first ball bounces back at 4 m/s and the second stays at rest
  2. The first ball stops and the second moves at 4 m/s Correct answer.
  3. Both balls move at 2 m/s in the original direction
  4. Both balls rebound at 4 m/s in opposite directions

Explanation

For an elastic head-on collision between equal masses, the moving ball transfers all its momentum and kinetic energy to the stationary one. The first ball stops and the second moves off at 4 m/s.

Question 39Mechanics

A 2 kg mass moving at 3 m/s collides with a stationary 1 kg mass and they move off together. How much kinetic energy is lost in the collision?

  1. 9 J
  2. 0 J
  3. 6 J
  4. 3 J Correct answer.

Explanation

Momentum conservation gives the common speed: (2×3)/3 = 2 m/s. Initial kinetic energy is ½×2×9 = 9 J and final is ½×3×4 = 6 J, so 3 J is lost as heat and deformation.

Question 40Mechanics

A particle moves in a straight line under a constant resultant force. Which quantity remains constant during the motion?

  1. Its acceleration Correct answer.
  2. Its velocity
  3. Its speed
  4. Its displacement

Explanation

By Newton's second law a constant resultant force on a fixed mass produces a constant acceleration. Speed, velocity and displacement all change as the particle moves.

Question 41Mechanics

A 10 kg crate is pulled 5 m across a floor by a rope making 60° with the horizontal, with tension 40 N. What is the work done by the tension?

  1. 173 J
  2. 100 J Correct answer.
  3. 0 J
  4. 200 J

Explanation

Work is the component of force along the displacement times the distance: W = Fd cos60° = 40 × 5 × 0.5 = 100 J. Only the horizontal component of the tension does work.

Question 42Mechanics

A pump raises 200 kg of water through a height of 10 m in 20 s. Taking g as 10 m/s², what is its useful output power?

  1. 2000 W
  2. 1000 W Correct answer.
  3. 100 W
  4. 20000 W

Explanation

The useful work is the gain in gravitational potential energy, mgh = 200 × 10 × 10 = 20000 J. Dividing by the time gives 20000/20 = 1000 W.

Question 43Mechanics

A particle of mass 2 kg moves under a single conservative force. Its potential energy falls by 50 J as it moves from point P to point Q. If it starts from rest at P, what is its kinetic energy at Q?

  1. 0 J
  2. 100 J
  3. 50 J Correct answer.
  4. 25 J

Explanation

For a conservative force, the loss in potential energy equals the gain in kinetic energy. Starting from rest, the kinetic energy at Q equals the 50 J decrease in potential energy.

Question 44Mechanics

A uniform rod of length 2 m is pivoted at one end and held horizontally. A force of 10 N acts vertically downward at the other end. What is the torque about the pivot?

  1. 5 N·m
  2. 40 N·m
  3. 20 N·m Correct answer.
  4. 10 N·m

Explanation

Torque is force times perpendicular distance from the pivot: τ = F × r = 10 × 2 = 20 N·m. The force is perpendicular to the rod, so the full length is the moment arm.

Question 45Mechanics

A flywheel of moment of inertia 4 kg·m² spins at 10 rad/s. What is its rotational kinetic energy?

  1. 40 J
  2. 400 J
  3. 20 J
  4. 200 J Correct answer.

Explanation

Rotational kinetic energy is ½Iω² = ½ × 4 × 10² = 200 J. The square of the angular velocity must be used, not the angular velocity itself.

Question 46Mechanics

A solid disc of mass 2 kg and radius 0.5 m rolls without slipping at 3 m/s. What is its total kinetic energy?

  1. 4.5 J
  2. 18 J
  3. 13.5 J Correct answer.
  4. 9 J

Explanation

For a solid disc I = ½mr², and rolling without slipping gives ω = v/r. The total kinetic energy is ½mv² + ½Iω² = ¾mv² = ¾ × 2 × 9 = 13.5 J.

Question 47Mechanics

A particle moves in simple harmonic motion with angular frequency 5 rad/s and amplitude 0.2 m. What is its maximum speed?

  1. 0.04 m/s
  2. 5.0 m/s
  3. 0.2 m/s
  4. 1.0 m/s Correct answer.

Explanation

In simple harmonic motion the maximum speed is v_max = ωA = 5 × 0.2 = 1.0 m/s, reached as the particle passes through the equilibrium position.

Question 48Mechanics

A simple pendulum has a period of 2 s on the Earth's surface. What is its period on the Moon, where the gravitational field strength is one sixth of that on Earth?

  1. 0.33 s
  2. 0.82 s
  3. 12 s
  4. 4.9 s Correct answer.

Explanation

The period of a simple pendulum is T = 2π√(L/g), so T ∝ 1/√g. With g reduced by a factor of 6, the period increases by √6 ≈ 2.45, giving 2 × 2.45 ≈ 4.9 s.

Question 49Mechanics

A body of mass 4 kg is in equilibrium under three coplanar forces. Two of the forces are 10 N east and 10 N north. What is the magnitude of the third force?

  1. 14 N Correct answer.
  2. 20 N
  3. 0 N
  4. 10 N

Explanation

For equilibrium the vector sum of all forces must be zero, so the third force must balance the resultant of the first two. That resultant is √(10² + 10²) ≈ 14 N, so the third force has magnitude about 14 N.

Question 50Mechanics

A block is placed on a rough horizontal turntable at a distance of 0.5 m from the axis. The coefficient of static friction is 0.5 and g is 10 m/s². At what angular speed does the block begin to slip?

  1. 1.6 rad/s
  2. 10 rad/s
  3. 3.2 rad/s Correct answer.
  4. 5.0 rad/s

Explanation

Friction provides the centripetal force, so μmg = mω²r, giving ω = √(μg/r) = √(0.5 × 10/0.5) = √10 ≈ 3.2 rad/s. Beyond this angular speed the required centripetal force exceeds the maximum static friction.