Laws Of Motion ( Physics ) MCQs – Latest Physics MCQs
Latest Physics MCQs
By practicing these MCQs of Laws Of Motion ( Physics ) MCQs – Latest Competitive MCQs , an individual for exams performs better than before. This post comprising of objective questions and answers related to “ Laws Of Motion ( Physics ) Mcqs “. As wise people believe “Perfect Practice make a Man Perfect”. It is therefore practice these mcqs of Physics to approach the success. Tab this page to check ” Laws Of Motion ( Physics )” for the preparation of competitive mcqs, FPSC mcqs, PPSC mcqs, SPSC mcqs, KPPSC mcqs, AJKPSC mcqs, BPSC mcqs, NTS mcqs, PTS mcqs, OTS mcqs, Atomic Energy mcqs, Pak Army mcqs, Pak Navy mcqs, CTS mcqs, ETEA mcqs and others.
Physics MCQs – Laws Of Motion ( Physics ) MCQs
The most occurred mcqs of Laws Of Motion ( ) in past papers. Past papers of Laws Of Motion ( Physics ) Mcqs. Past papers of Laws Of Motion ( Physics ) Mcqs . Mcqs are the necessary part of any competitive / job related exams. The Mcqs having specific numbers in any written test. It is therefore everyone have to learn / remember the related Laws Of Motion ( Physics ) Mcqs. The Important series of Laws Of Motion ( Physics ) Mcqs are given below:
Laws of Motion Basics
1. Which of the following laws of motion is related to inertia?
a) First law
b) Second Law
c) Third Law
d) Fourth Law
Answer: a
Explanation: The first law of motion states that a body remains in the state of motion or in the state of rest until and unless an external force is applied on it. This is also known as the law of inertia. Hence the answer is, the first law.
2. Which law of Newton helps in finding the force on a body?
a) First law
b) Second Law
c) Third Law
d) Fourth Law
Answer: b
Explanation: The second law of motion states that the net force applied on a body is proportional to the rate of change of momentum. On further experimentation, it was found that the force applied on a body is equal to the rate of change of momentum.
3. Which law of Newton helps in finding the reaction forces on a body?
a) First law
b) Second Law
c) Third Law
d) Fourth Law
Answer: c
Explanation: The third law of motion states that for every action there is an equal and opposite reaction. This law helps us in finding the reaction forces on a body. A classic example is the way we walk. We need to push the ground for walking and when we do so we experience an equal and opposite force on ourselves which helps us in walking.
4. The second law of motion, in mathematical form can be written as ____
a) F = dp/dt
b) F = ma
c) F = v(dm/dt)
d) F = mv
Answer: a
Explanation: The second law of motion states that the net force applied on a body is equal to the rate of change of momentum. Momentum is usually represented by ‘p’. Hence, the answer is F = dp/dt.
5. When we walk on a boat in still water, the boat will ______
a) Move ahead
b) Move backwards
c) Not move
d) Move sideways
Answer: b
Explanation: The third law of motion applies in this case. According to the third law of motion, for every action, there is an equal and opposite reaction. When we walk on the boat, the boat experiences an equal and opposite reaction force. Since very little resistance is offered by the still water, the boat will move backwards.
6. Which one of the following is not an example of the third law of motion?
a) Walking
b) Skiing
c) Walking on a boat
d) Cycling
Answer: b
Explanation: The third law of motion does not apply to skiing as in skiing we do not apply any force on the ground. The motion is caused by gravity and extremely less friction. In all the other cases, a force is applied on the ground or the other body, the reaction of which causes the motion.
7. Which of the following is the correct formulation for the second law of motion?
a) F = m(dv/dt)
b) F = ma
c) F = v(dm/dt) + ma
d) F = mv2
Answer: c
Explanation: The second law of motion states that the net force applied on a body is equal to the rate of change of momentum. Hence, F = dp/dt. p = mv. Therefore, F = m(dv/dt) + v(dm/dt) = v(dm/dt) + ma.
Newton’s First Law of Motion
1. What causes the motion of a body which is initially in the state of rest?
a) Force
b) Displacement
c) Speed
d) Velocity
Answer: a
Explanation: The first law of motion states that a body remains in the state of motion or in the state of rest until and unless an external force is applied on it. Hence, the answer is force. This is also known as the law of inertia.
2. People sitting in a moving bus experience a jerk when the bus stops. This is due to _____
a) Inertia of motion
b) Inertia of rest
c) Inertia of turning
d) Inertia of acceleration
Answer: a
Explanation: When the bus stops, the people sitting in it experience a jerk. This is because, while the bus was moving, the people were moving with it. Hence, they were having an inertia of motion. When the bus stops, the inertia of the bus changes from that of motion to that of rest. But the inertia of the people still remains that of motion. Hence, they experience a jerk.
3. Passengers sitting in a stationary car experience a jerk when the car suddenly starts. This is due to _____
a) Inertia of motion
b) Inertia of rest
c) Inertia of turning
d) Inertia of acceleration
Answer: b
Explanation: When the car starts, the people sitting in it experience a jerk. This is because, while the car was stationary, the people were stationary with it. Hence, they were having an inertia of rest. When the car starts, the inertia of the car changes from that of rest to that of motion. But the inertia of the people still remains that of rest. Hence, they experience a jerk.
4. In the following figure, what will happen to the ball hanging from the roof of the car if the car suddenly moves towards left (direction shown by arrow)?
a) Ball moves towards right
b) Ball moves towards left
c) Ball does not move
d) Ball moves out of the paper
Answer: a
Explanation: Since the system was initially at rest, the inertia of the ball is that of rest. When the car suddenly moves the inertia of the car changes but not that of the ball. Hence the ball moves towards right.
6. A straight moving bus takes a sharp right turn. What will happen to the passengers sitting inside the bus?
a) They will tilt rightwards
b) They will tilt leftwards
c) They will stay the way they were
d) They will start jumping
Answer: b
Explanation: When the bus takes a sharp right turn, the inertia of the bus changes. But the inertia of the passengers is still towards the straight direction. Hence, they will relatively move towards the left.
6. Why do we not experience any leaning when a train takes a turn?
a) Because the train is powerful
b) Because of large turning radius
c) Because the train does not turn
d) Because the driver is smart
Answer: b
Explanation: The train’s turning radius is large as compared to the turning radii of normal vehicles. Hence, there is no sharp or sudden turning. Therefore, the passengers do not experience any leaning.
7. Inertia is _____
a) Property of mass to remain unchanged
b) Property of mass to change continuously
c) Property of mass to accelerate
d) Tendency of mass to accelerate
Answer: c
Explanation: Inertia is the property of mass to remain unchanged. Inertia is because of which a mass continues to remain in its original state in absence of any external force. Inertia of a body can be changed only by an external force.
Newton’s Second Law of Motion
1. What is the force applied on a body with 5 kg of mass and an acceleration of 7 m/s2?
a) 35 N
b) 5 N
c) 7 N
d) 0 N
Answer: a
Explanation: According to the second law of motion, the force on a body is equal to the rate change of its momentum. On simplifying we get, F = ma. Therefore, Force = 5 x 7 = 35 N.
2. Unit of force is _____
a) Newton
b) Pascal
c) Byte
d) Gram
Answer: a
Explanation: The unit of force is newton. This unit has been given after the name of the famous scientist Sir Isaac Newton who had given the three laws of motion. The force on anybody can be found with the help of the second law of motion.
3. The unit ‘Newton’ is equivalent to ______
a) Kg-m/s2
b) Kg-m/s
c) Kg/m/s2
d) Kg2-m/s2
Answer: a
Explanation: From the second law of motion we get that F = ma, when the mass is not changing. Putting in the units, we get, Newton = Kg-m/s2.
4. If the force acting on a body is 10 N, and the acceleration is 4 m/s2, what can be the mass of the body?
a) 2.5 Kg
b) 25 Kg
c) 0.25 Kg
d) 5 Kg
Answer: a
Explanation: From the second law of motion we get that F = ma, when the mass is not changing. Putting in the values, we get, Force = 10 = m x 4. Which will result in m = 2.5 Kg.
5. If the force acting on a body is 50 N, and the mass is 5 kg, what can be the acceleration of the body?
a) 10 m/s2
b) 80 m/s2
c) 8 m/s2
d) 0.8 m/s2
Answer: a
Explanation: From the second law of motion we get that F = ma, when the mass is not changing. Putting in the values, we get, Force = 10 = 5 x a. Which will result in a = 10 m/s2.
6. An example of variable mass system is _____
a) A car moving
b) A rocket taking off
c) A bicycle moving
d) A man walking
Answer: b
Explanation: In case of a rocket taking off, the mass of the fuel is large and cannot be neglected. As the rocket starts moving, a large amount of fuel is getting burnt out from the nozzle, hence the total mass decreases. Hence it is a variable mass system.
7. How do we calculate force in a variable mass constant velocity system?
a) F = ma
b) F = mv
c) F = v(dm/dt)
d) F = m/t
Answer: c
Explanation: The general expression for force is F = dp/dt. On solving we get, F = m(dv/dt) + v(dm/dt). Since the system is constant velocity, hence dv/dt = 0. What remains is F = v(dm/dt).
Newton’s Third Law of Motion
1. The forces involved in Newton’s third law act ____
a) On the same object
b) On different objects
c) In same direction
d) On five bodies
Answer: b
Explanation: The two forces involved in Newton’s third law are the cause force and the reaction force. The cause force acts on the contact surface or the contact body by the parent body. Whereas the reaction force acts on the parent body by the contact body.
2. Two bodies in contact experience forces in ________
a) Same direction
b) Opposite directions
c) Perpendicular directions
d) Five different directions
Answer: b
Explanation: The two bodies in contact will follow Newton’s third law of motion. The third law states that for every action there is an equal and opposite reaction. The two bodies will experience each other’s reaction forces in opposite directions.
3. A batsman hits a ball with a force a 5 N. What force does the bat experience?
a) 5 N
b) 10 N
c) 15 N
d) 20 N
Answer: a
Explanation: From Newton’s third law we know that for every for every action, there is an equal and opposite reaction. From this we can say that the bat experiences a force of 5 N.
4. A driver hits a light pole with a force a 100 N. What force does the car experience?
a) 100 N
b) 10 N
c) 150 N
d) 200 N
Answer: a
Explanation: From Newton’s third law we know that for every for every action, there is an equal and opposite reaction. From this we can say that the car experiences a force of 100 N by the light pole.
5. A truck with a mass of 2500 Kg travelling with an acceleration of 5 m/s2 hits a scooter. What force does the truck experience?
a) 12500 N
b) 500 N
c) 10000 N
d) 2500 N
Answer: a
Explanation: From Newton’ second law we get force on scooter = 2500 x 5 = 12500 N. From Newton’s third law we know that for every for every action, there is an equal and opposite reaction. From this we can say that the truck experiences a force of 5 N.
6. A man and a kid accidentally hit each other. What is true about the forces experienced by them?
a) They are equal in magnitude
b) They are different in magnitude
c) They are same in direction
d) They are at an angle of 1.57 rad
Answer: b
Explanation: From the third law of motion, we know that the cause force and the reaction forces are equal in magnitude and opposite in direction. Hence, from this knowledge, we can say that the man and the kid will experience forces in opposite directions and in equal magnitude.
7. A man is standing still. The force by the man on the earth is F1→. The force by the earth on the man is F2→. Which one of the following is true?
a) F1→=F2→
b) F1→=−F2→
c) F1→=5(F2→)
d) 2(F1→)=F2→
Answer: b
Explanation: According to the third law of motion, every action has an equal and opposite reaction. Hence every action force is equal in magnitude to its reaction but in opposite direction. Hence F1→=−F2→ is the correct answer.
Conservation of Momentum
1. Two bodies moving with constant velocities collide with each other. Which of the following quantities remain conserved?
a) Momentum
b) Speed
c) Force
d) Velocity
Answer: a
Explanation: Two bodies collide in the absence of any external force. In this case the momentum will remain constant because there is no force, hence, there is no change in momentum. The velocity and speed of the bodies might change after collision.
2. A ball is moving with a constant velocity. After some time, it collides with a wall. Which one of the following remains conserved except momentum?
a) Energy
b) Displacement
c) Power
d) Force
Answer: a
Explanation: Apart from the momentum, the energy also remains conserved during collision. As a matter of fact, the energy of a system often remains conserved.
3. A variable mass body with an initial mass of 5 kg is moving with a velocity of 5 m/s initially, after some time the velocity increases to 10 m/s, what is the new mass if the body is moving in the absence of any external force?
a) 2.5 Kg
b) 5 Kg
c) 7.5 Kg
d) 10 Kg
Answer: a
Explanation: The body is moving in the absence of any external force thus the momentum remains conserved. m1v1 = m2v2. v1 = 5 m/s, m1 = 5 Kg, v2 = 10 m/s. On solving, we get, m2 = 2.5 kg. Hence, the correct answer is 2.5 Kg.
4. Two bodies of masses 2 Kg and 7 Kg are moving with velocities of 2 m/s and 7 m/s respectively. What is the total momentum of the system in Kg-m/s?
a) 50
b) 53
c) 28
d) 0
Answer: b
Explanation: Both the bodies are moving with constant velocity, hence both of them have momentum. The momentum of the system is the sum of the momenta of the bodies. Hence total momentum = 2 x 2 + 7 x 7 = 53 Kg-m/s.
5. What is the plural of the word ‘momentum’?
a) Momenta
b) Momentums
c) Moments
d) Momentuma
Answer: a
Explanation: The plural for momentum is momenta and not momentums. Momenta, being a plural, is usually used in cases where we need to address a more than one momentum. This situation can possibly arise in systems having more than one moving body.
6. Two bodies are accelerating towards each other. After sometime they collide. Which one of the following statements is true about the system?
a) The total momentum remains conserved about the instant of collision
b) The total momentum remains conserved during collision
c) The total momentum does not remain conserved
d) The total momentum remains conserved
Answer: a
Explanation: The two bodies are accelerating and they collide. Since they are accelerating the total momentum does not remain conserved during the motion. But at the instant of collision, both the bodies have a constant velocity. Hence, just before and just after the collision, the total momentum will remain conserved.
Motion In A Straight Line MCQs
7. When a body collides with a wall or the ground, what assumption do we make?
a) The mass of the body is not negligible
b) The body is stationary
c) The mass of the body is negligible as compared to the mass of the wall or the ground
d) The body is perfect
Answer: c
Explanation: When a body collides with a wall or the ground, we consider that the mass of the body is negligible as compared to the mass of the wall or the ground. We also make this assumption when something like a feather, which has a very small mass collides with a truck, which, comparatively, has a huge mass.
8. A variable mass body with an initial mass of 10 kg is moving with a velocity of 7 m/s initially, after some time the velocity increases to 14 m/s, what is the new mass if the body is moving in the absence of any external force?
a) 2.5 Kg
b) 5 Kg
c) 7.5 Kg
d) 10 Kg
Answer: b
Explanation: The body is moving in the absence of any external force thus the momentum remains conserved. m1v1 = m2v2. v1 = 7 m/s, m1 = 10 Kg, v2 = 14 m/s. On solving, we get, m2 = 5 kg. Hence, the correct answer is 5 Kg.
Equilibrium of a Particle
1. The first condition of equilibrium of a body is ___
a) Sum of all force on a body should be zero
b) Sum of all moments on a body should be zero
c) Sum of the initial and final force should be zero
d) Relative difference of forces should be zero
Answer: a
Explanation: The first condition for a body to exist in equilibrium is that the sum of all forces on the body must be zero. Which means that the resultant force on a body should be zero.
2. The second condition of equilibrium of a body is ___
a) Sum of all force on a body should be zero
b) Sum of all moments on a body should be zero
c) Sum of the initial and final force should be zero
d) Relative difference of forces should be zero
Answer: b
Explanation: The second condition for a body to exist in equilibrium is that the sum of all moments on the body must be zero. Which means that the resultant moment on a body should be zero.
3. What can be said about a body which is moving with a constant velocity?
a) It is in static equilibrium
b) It is in dynamic equilibrium
c) It is in the state of non-equilibrium
d) Its distance is conserved
Answer: b
Explanation: When a body is moving with constant velocity, there is no net force or moment acting on it. Hence, the body is in equilibrium. But since the body is moving, the equilibrium is known as dynamic equilibrium. Static equilibrium occurs when the body is at rest.
4. Two forces are acting on a body. For the body to remain in equilibrium, the forces have to be ____
a) Equal in magnitude and opposite in direction
b) Equal in direction and opposite in magnitude
c) In the same direction
d) In perpendicular directions
Answer: a
Explanation: Only when the forces are equal in magnitude and opposite in direction, the net force will be zero on the body. Since there is no moment, we need not care about the second condition of equilibrium. The body is in equilibrium only when the net force acting on it is zero which is satisfied only in this manner.
5. Two forces act on a ball. One of the forces is positive and acts towards right, the other one acts towards left and is ______
a) Negative
b) Positive
c) Neutral
d) Having a magnitude of 5 N
Answer: b
Explanation: The force has to be positive. The reason is that the forces are acting in opposite directions. Which means that the direction of the forces has been specified and they are bound to cancel each other out. So, if, the second force is negative, the net direction will be towards right and the body will not be able to stay in equilibrium.
6. Two forces act on a body. One of them is 7î – 13ĵ. What is the value of the other force?
a) 7î – 13ĵ
b) -7î + 13ĵ
c) 7î + 13ĵ
d) -7î – 13ĵ
Answer: a
Explanation: For the body to remain in equilibrium, the total force on it should be zero. As one of the forces is given, the other force can be found out by subtracting it from zero. Hence the answer is -7î + 13ĵ.
7. Three forces act on a body. Two of them are 7î – 13ĵN and 2î – 11ĵ. What is the value of the other force?
a) -9î + 24ĵ
b) -24î + 9ĵ
c) 24î + 9ĵ
d) -9î – 24ĵ
Answer: a
Explanation: For the body to remain in equilibrium, the total force on it should be zero. As two of the forcesare given, the other force can be found out by subtracting the sum of both the given forces from zero. Hence the answer is -9î + 24ĵ.
8. If a body returns to its original state of equilibrium after giving it a small displacement, the equilibrium is known as ______
a) Stable equilibrium
b) Unstable Equilibrium
c) Neutral Equilibrium
d) Simple equilibrium
Answer: a
Explanation: The body is said to be in the state of stable equilibrium if it returns to its original equilibrium after giving it a slight displacement. In unstable equilibrium, the body does not return to its original equilibrium and moreover also does not achieve any other equilibrium. In neutral equilibrium, the body attains a new equilibrium every time it is displaced.
9. A set of forces are acting on a body in equilibrium. Which one of the following is true?
a) The vector sum of the forces is zero
b) The scalar sum of the force is zero
c) All the forces are zero
d) All the forces are equal and opposite in direction to each other
Answer: a
Explanation: When a body is in equilibrium, the sum of all the forces is zero. The sum of all the forces relates to the vector sum of all the forces and not any other sum. The scalar sum is always positive hence it cannot be zero. The forces need not be zero for the body to be in equilibrium, only the vector sum has to be zero. The same goes with the magnitude and direction of the forces.
Non-Uniform Circular Motion
1. A stone tie with a string held at one end is being rotated at a constant angular velocity in the air. The tangential velocity will remain constant if _______
a) The plane of motion of the stone is parallel to the ground
b) The plane of motion of the stone is perpendicular to the ground
c) The plane of motion of the stone is at an angle of 45 degrees to the ground
d) The tangential velocity is independent of the plane of motion
Answer: a
Explanation: When the plane motion of the stone is parallel to the ground, the tangential velocity experiences acceleration in two directions, one towards the centre and other towards the ground. Both these directions are perpendicular to the direction of the tangential velocity. Hence the tangential velocity will not change.
2. A ball tied at the end of a perfect string tied tightly (assume fixed) to a wooden bar at the other end is rotating with constant angular velocity. Its tangential velocity will _______
a) Increase with time
b) Decrease with time
c) Will remain constant
d) Will decrease exponentially
Answer: b
Explanation: As the other end of the string is fixed to the wooden bar, the motion will cause the string to wrap itself around the bar. This will result in decrease in the effective radius of the circular motion. Tangential velocity v = ωr, the tangential velocity will decrease with time.
3. A rocket takes off from the earth and continues to move in a circular orbit with the thrusters on. What can be said about the angular velocity of the rocket?
a) It increases
b) It decreases
c) It remains constant
d) It changes abruptly
Answer: a
Explanation: When the rocket is in the orbit with the thrusters on, there is a tangential force that the rocket experiences. This force will result in increasing the tangential velocity. Since the angular velocity is directly proportional to the tangential velocity, the angular velocity will also increase.
4. The radius of a body moving in a circle with constant angular velocity is given by r = 4t2, with respect to time. What is the magnitude of the tangential velocity at t = 2s, if the angular velocity is 7 rad/s?
a) 112
b) 113
c) 56
d) 28
Answer: a
Explanation: The tangential velocity is given as v = ωr. At t = 2s, r = 16 units. The angular velocity is 7 rad/s. Hence, the tangential velocity, v = 7 x 16 = 112 units/s.
5. A car moving around a tree has the distance from the tree defined as r = 5t2 + 7. What is the magnitude of the centripetal acceleration at t = 2s, if the angular velocity is 2 rad/s.
a) 102
b) 108
c) 59
d) 54
Answer: b
Explanation: The centripetal acceleration is given as ac = rω2. Here, we have r = 5t2 + 7 = 27 units at t = 2s. Angular velocity is 2 rad/s. On substituting all the values, we get, the acceleration as 108 units/s2.
6. The tangential velocity in a circular motion change as v = 2t2 – 7 with the radius being equal to 3 m. What is the angular velocity at t = 1 s in rad/s?
a) -5/3
b) -2/3
c) 3
d) -3/5
Answer: a
Explanation: The angular velocity is given as, ω = v/r. Hence, the function for angular velocity is ω = (2t2 – 7)/3. On substituting, the suitable values, we will get the angular velocity as -5/3 rad/s.
7. The tangential velocity of a body in a non-uniform circular motion varies as v = 7t2 – 2v with the radius being equal to 21 m. What is the angular acceleration at t = 2 s in rad/s2?
a) 4/3
b) 5/3
c) 4
d) 7/5
Answer: a
Explanation: The angular velocity is given as, ω = v/r. Hence, the function for angular velocity is ω = (7t2 – 2)/21. On differentiating this expression, we will get the angular acceleration as t2/3 On substituting, the suitable values, we will get the angular acceleration as 4/3 rad/s2.
8. Which of the following is a suitable word to describe the motion of a rotating ball tied to rope tied tightly to a fixed support?
a) Spiral motion
b) Circular motion
c) Elliptic motion
d) Uniform motion
Answer: a
Explanation: A ball, tied to a rope, rotating around a fixed support will cause the rope to wind itself around the support. Hence, the motion will be circular with decreasing radius. This motion will cause the path look like a spiral. Hence the motion is spiral in nature.
9. A block of mass 5 Kg, exhibits circular motion with the mass decreasing at the rate of 0.5 Kg/s. At what time the centripetal force will be zero on the block?
a) At 10 s
b) At 5 s
c) At 1 s
d) At 7 s
Answer: a
Explanation: The centripetal force on a body is directly proportional to its mass with a proportionality constant of 1. Hence the centripetal force will be zero when the mass is zero. The function for the mass at t seconds is m = 5 – 0.5t. On equating this to zero we get, t = 10 s. this is the required time.
10. A box of mass 10 Kg, moves in circular motion with the mass function as m = 7t. The function for the radius is r = 2t2. By what factor does the centripetal force exceed the square of the tangential velocity at t = 2 s?
a) 7/4
b) 7/5
c) 7/2
d) 7
Answer: a
Explanation: The centripetal force on a body is given as Fc = mv2/r. Hence, the required factor is the ratio of the mass to the radius at t = 2s. Hence, required factor = m/r = 7/2t. On substituting the values, we get the factor as 7/4.