86 free MCQs on Laws of Motion, each with its own worked answer and explanation. Newton's three laws, friction, circular motion, and free body diagrams.
Take the timed Laws of Motion chapterwise test →86 practice questions on Laws of Motion, sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the Laws of Motion notes.
Free-body diagram of a block on an incline: weight (mg) resolves into mg sinθ along the slope and mg cosθ into the slope, balanced by the normal force N and friction f.
Q1.
Aristotle's law of motion incorrectly assumed that the natural state of a moving body, when left to itself, is:
Q2.
Aristotle held that a moving body comes to rest once the applied force is removed. This view (Aristotle's fallacy) is wrong because it ignores:
Q3.
Whose reasoning corrected Aristotle's fallacy and led to the law of inertia?
Q4.
The physical quantity that measures the inertia of a body is its:
Q5.
A body moving with uniform velocity continues to do so unless acted upon by:
Q6.
Friction that acts on a body just when it is about to start sliding is called:
Q7.
The coefficient of friction μ and the angle of friction θ are related by:
Q8.
According to Newton's second law, the rate of change of momentum of a body equals the:
Q9.
Newton's first law of motion is also called the law of:
Q10.
Which of the following has the most inertia?
Q12.
F = ma is a statement of Newton's:
Q13.
A book rests on a table. The reaction force to the book's weight acts on:
Q14.
When a bus suddenly brakes, passengers lean forward due to:
Q15.
The force of friction always acts:
Q16.
A force of 10 N acts on a 2 kg mass. Its acceleration is:
Q17.
Which type of friction is least among these three?
Q18.
A bullet fired from a gun causes the gun to recoil. This is an example of:
Q19.
The weight of a body is:
Q20.
An object in equilibrium has:
Q21.
The coefficient of friction between two surfaces depends on:
Q22.
A 60 kg person stands in an elevator. Normal force equals weight when:
Q24.
A man pushes a wall with 30 N force. The wall pushes back with:
Q25.
Maximum static friction is always _____ kinetic friction:
Q26.
Momentum of a 2 kg ball moving at 10 m/s is:
Q27.
When two objects collide and stick together, it is called:
Q28.
A stationary block on a rough surface does not move when a small horizontal force is applied. This means:
Q29.
A constant force of 20 N acts on a 4 kg body for 3 s. The impulse delivered to the body is:
Q30.
A 2 kg block slides down a frictionless incline of 30°. Its acceleration is (g = 10 m s<sup>-2</sup>):
Q31.
A 2 kg object moving at 5 m s<sup>-1</sup> collides with and sticks to a stationary 3 kg object. Their common velocity is:
Q32.
A lift moving upward decelerates at 2 m s<sup>-2</sup>. The apparent weight of a 50 kg person in it is (g = 10 m s<sup>-2</sup>):
Q33.
A 5 kg block rests on a rough surface with coefficient of friction 0.4. The minimum horizontal force needed to just start it moving is (g = 10 m s<sup>-2</sup>):
Q34.
Two blocks of mass 3 kg and 5 kg are connected by string. A force of 40 N pulls the 5 kg block. Acceleration of system is:
Q35.
Tension in string connecting 3 kg and 5 kg blocks pulled by 40 N (no friction):
Q36.
A 70 kg person stands in elevator accelerating upward at 3 m/s<sup>2.</sup> Normal force on person is (g=10):
Q37.
A block on a rough inclined plane just starts to slide when angle = theta. Coefficient of static friction equals:
Q38.
A body of mass 5 kg moving at 10 m/s is brought to rest in 2 s. Average braking force is:
Q39.
Two masses m<sub>1</sub>=4 kg and m<sub>2</sub>=6 kg are on Atwood machine. Acceleration is (g=10):
Q40.
A cricket ball (0.16 kg) bowled at 30 m/s is hit back at 40 m/s. The impulse on ball is:
Q41.
A 10 kg block on a rough horizontal surface with mu_k = 0.3. Force needed to keep it moving at constant velocity (g=10):
Q42.
Conservation of momentum applies when:
Q43.
A 1200 kg car moving at 20 m/s brakes to stop in 50 m. Braking force is:
Q44.
If friction force is 40 N on a 10 kg block on a horizontal surface, coefficient of friction is (g=10):
Q45.
A person weighing 500 N is in a lift moving upward at constant velocity. The normal force exerted by floor is:
Q46.
Action and reaction forces in Newton's third law act on:
Q47.
A 0.5 kg ball hits a wall at 10 m/s and bounces back at 10 m/s. Contact time = 0.01 s. Force on ball is:
Q48.
A 60 kg boy jumps from a stationary boat (40 kg) at 7.5 m/s. Velocity of boat recoils at:
Q49.
On a rough incline (theta=30 deg, mu=0.5), normal force on 4 kg block is (g=10):
Q50.
Net force on a 5 kg block accelerating at 3 m/s<sup>2</sup> is:
Q51.
Two equal masses moving toward each other at equal speeds collide and stick. Final velocity is:
Q52.
A 50 kg block is pushed along floor with mu_k=0.2. Force needed for acceleration of 1 m/s<sup>2</sup> is (g=10):
Q53.
Momentum has the same units as:
Q54.
A block of mass 4 kg is on a rough incline of 37° (sin37° = 0.6, cos37° = 0.8) with μ = 0.5. Its acceleration down the incline is (g = 10 m s<sup>-2</sup>):
Q55.
A 2 kg block on a frictionless table is connected over a pulley to a 3 kg mass hanging freely. The tension in the string is (g = 10 m s<sup>-2</sup>):
Q56.
A 0.1 kg ball moving at 20 m s<sup>-1</sup> is struck and rebounds along the same line at 30 m s<sup>-1</sup>. If the contact time is 0.02 s, the average force on the ball is:
Q57.
A machine gun fires 20 bullets per second, each of mass 40 g at 400 m s<sup>-1</sup>. The force needed to hold the gun steady is:
Q58.
Three blocks of 1 kg, 2 kg and 3 kg are joined in a line by strings on a frictionless surface. A 12 N force pulls the 3 kg end. The tension in the string attached to the 1 kg block is:
Q59.
Three blocks (2 kg, 3 kg, 5 kg) in series pulled by 100 N. Force between 5 kg and 3 kg blocks is:
Q60.
Block A (3 kg) on block B (5 kg) on frictionless floor. mu between A and B = 0.4. Max force on B for A not to slip (g=10):
Q61.
A 2 kg block is pressed against a vertical wall by horizontal force F. mu=0.5. Minimum F to prevent sliding (g=10):
Q62.
A rocket exhausts fuel at 10 kg/s with exhaust speed 200 m/s relative to rocket. Thrust is:
Q63.
A block on incline (theta=45 deg, mu=0.5) is pushed up. Deceleration while going up (g=10):
Q64.
Two masses m and 2m on an Atwood machine. System released from rest. Acceleration is:
Q65.
A ball of mass m strikes a wall at 45 deg and bounces at 45 deg with same speed v. Impulse from wall is:
Q66.
A man in lift reads W<sub>1</sub> when going up with acceleration a, and W<sub>2</sub> when going down with same acceleration a. His true weight is:
Q67.
A gun fires 10 bullets per second, each 50 g at 500 m/s. Average force on gun is:
Q68.
Monkey of mass m hangs on rope. Below it hangs a box of mass M. Rope breaks at T<sub>max</sub>. Max upward acceleration:
Q69.
A 5 kg block has force F = 3t N (t in seconds) applied to it on a frictionless surface. Velocity at t=4 s is:
Q70.
Blocks m<sub>1</sub>=2 kg and m<sub>2</sub>=4 kg on rough surface mu=0.25. 18 N force pulls m<sub>1</sub> forward. Acceleration (g=10):
Q71.
A 2000 kg car changes speed from 30 m/s to 20 m/s in 4 s. Average braking force is:
Q72.
A ball of mass m on string of length L moves in vertical circle at speed v at the top. Tension at top is:
Q73.
Minimum speed at top of vertical circular loop of radius 5 m to maintain contact (g=10):
Q74.
Two blocks hang from string through a hole in frictionless table: 1 kg on table, 2 kg hanging. Acceleration when released (g=10):
Q75.
A block of mass 5 kg on table is connected by string over edge to hanging mass 3 kg. mu_k=0.2 on table. Acceleration (g=10):
Q76.
A 3 kg block rests on a 2 kg block on a smooth floor. mu between blocks = 0.4. A 10 N force is applied to the lower block. Does the upper block slip? (g=10)
Q77.
A particle of mass m hits a fixed wall at speed v at angle 60 deg to normal and bounces off at 60 deg to normal. Coefficient of restitution is 1. Impulse magnitude:
Q78.
A 500 kg boat and a 50 kg man are stationary. Man runs forward at 5 m/s relative to boat. Speed of boat is:
Q79.
A 40 kg monkey climbs a rope with an upward acceleration of 2 m/s² (g = 10 m/s²). The tension in the rope is:
Q80.
A 60 kg person stands in a lift accelerating downward at 2 m/s² (g = 10 m/s²). The apparent weight (reading of the scale) is:
Q81.
In an Atwood machine, masses 5 kg and 3 kg hang over a frictionless pulley (g = 10 m/s²). The tension in the string is:
Q82.
A 10 kg block rests on a floor with μ = 0.5. A horizontal force of 40 N is applied (g = 10 m/s²). The friction force acting on the block is:
Q83.
A 0.2 kg ball hits a wall at 10 m/s and rebounds at 10 m/s. The magnitude of the impulse imparted to the ball is:
Q84.
A block rests on the floor of a truck (g = 10 m/s²). If the truck decelerates at 5 m/s², the minimum coefficient of friction that keeps the block from sliding forward is:
Q85.
A uniform chain of mass 3 kg on a frictionless table is pulled by a horizontal force of 6 N applied at one end. The tension at the midpoint of the chain is:
Q86.
Two blocks of 3 kg and 2 kg are placed in contact on a frictionless surface. A horizontal force of 10 N is applied on the 3 kg block. The contact force between the blocks is:
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