# Laws of Motion Multiple Choice Questions

Q1. A car goes around a flat curved road. Which of the following can provide for the centripetal force?

1. weight
2. Friction
3. Electrostatic attraction
4. Air resistance

Q2. A mass of 100 kg is resting on a rough inclined plane of 60o. If the coefficient of friction is 0.5, then the least force acting parallel to the plane to keep the mass in equilibrium is

1. 603.7 N
2. 605.5 N
3. 500 N
4. 100 N

Q3.The inability of body to change its state of uniform motion or rest is known as

1. Law of inertia
2. Newton’s third law of motion
3. Newton’s law of gravitation
4. Newton’s second law of motion

Q4. A train is moving along a horizontal track. A pendolum suspended from the roof of the train makes an angle of 5o with the vertical. The acceleration of the train is

1. 0.87 ms-2
2. 0.70 ms-2
3. 0.60 ms-2
4. 1 ms-2

Q5. A book is lying on the table. What is the angle between the action of the book on the table and reaction of table on the book?

1. Zero degree
2. Ninty degree
3. Hundred eighty degrees
4. Forty five degree

Q6. A lift is moving down with the acceleration 3 m/s2. A ball is released 1.7 m above the the lift floor. How long will it take to hit the lift floor.

1. 0.5 s
2. 1.7 s
3.  0.71 s
4. 7.1 s

Q7. The SI unit of impolse is

1. Ns
2. Nm2
3. Nm
4. Nm-1

Q8. After the body starts moving, the friction involved with motion is

1. Static Friction
2. Kinetic Friction
3. Rolling Friction
4. Sliding friction

Q9. When a wheel rolls on a level road, the direction of frictional force at the point of contact of wheel and ground is

1. forward direction
2. backward direction
3. along the tangent to the wheel
4. along the centre of the wheel

Q10. The mass of lift is 1000 kg. The tension in the cable of the lift while the lift is moving upward with the acceleration of 2 ms-2 is:

1. 20000 N
2. 9800 N
3. 11800 N
4. 11000 N

Q11. Which of the following is called a fictitious force?

1. Centripetal force
2. Centrifugal force
3. Gravitational force
4. Frictional force

Q12. A man in the lift weighs more, when the lift

1. begins to go up
2. moves up with constant velocity
3. moves down with constant velocity
4. is in free fall

Q13. If newton is the unit of force in MKS system then, in CGS system 1N= ______ dyne

1. 105
2. 104
3. 106
4. 103

Q14. It is easier to roll a cylindrical container than to poll it along the road because

1. Large contact area between cylinder and surface
2. Rolling friction is lesser compared to sliding friction
3. Sliding friction is more than rolling friction
4. Cylindrical container rolls automatically after small push

Q15. When an apple tree is shaken apples are detached from the branches because:

1. There is no option to them except to fall down
2. Branches tend to continue in the state of rest and apples go into motion
3. Apples experience a net downward poll towards ground
4. Apples tend to continue in the state of rest and branches go into motion

Q16. A block of mass m is pushed by applying a force F at an angle θ with the horizontal surface. The normal force on the block is given as –

1. F = mg + F sin θ
2. F = mg – F sin θ
3. F = F sin θ
4. F = mg

Q17. A ball of mass 150 g moving at 10 ms-1is stopped by a force which acts on it for 0.1 s, then the impolsive force is

1. 70N
2. 15 N
3. 150 N
4. 1500 N

Q18. A machine gun has a mass of 20 kg fires 35 g bollets at the rate of 400 bollets per second with a speed of 400ms-1 .What force must be applied to the gun to keep in the position?

1. 5600 N
2. 5800 N
3. 560 N
4. 56 N

Q19. In cgs system the gravitational unit of force is gram weight (g wt).Then 1g wt (or g f) =_______ dyne.

1. 980 dyne
2. 9.8 dyne
3. 9.8 N
4. 980 N

Q20. Which of the conditions shows that the particles are in equilibrium state for two forces F1 and F2 acting on the body?

1.  F= -F2
2. F1 = F2
3. 2F1=F2
4. F1= 2F2

Q21. A cyclist bends while taking a sharp turn so that

1. friction is reduced
2. component of his weight provides centripetal force
3. he can go fast
4. it looks nice

Q22. In which direction does the friction act, when a block is moved down the inclined plane?

1. Parallel to inclined plane
2. Normal to inclined plane
3. Parallel and in upward direction along the inclined plane
4. Normal and in upward direction along the inclined plane

Q23. The component of contact force parallel to the surface in contact is called ______ .

1. Reaction force
2. Friction
3. Gravitational force
4. Centrifugal force

Q24. A block of mass 1 kg lies on a horizontal surface in a truck. The coefficient of static friction between the block and the surface is 0.6. If the acceleration of the truck is 5 ms-2, the frictional force acting on the block is

1. 4 N
2. 5 N
3. 6 N
4. 7 N

Q25. A particle moves in a circle with a constant speed of 6m /s. Its centripetal acceleration is 120 m/s2, The radius of the circle is

1. 30 cm
2. 300 cm
3. 20 cm
4. 200 cm

Q26. The maximum speed at which a car can turn round a curve of 40 m radius on a level road is: (Given: coefficient of friction between the tyres and road is 0.5)

1. 14 m/s
2. 20 m/s
3. 21 m/s
4. 26 m/s

Q27. The principle of working of a rocket is based on

1. conservation of linear momentum and third law of motion
2. conservation of energy
3. conservation of mass
4. conservation of charge

Q28. If two ends of a spring balance are polled by a force of 10N, then the reading of the spring balance will be

1. 0 N
2. 10 N
3. 20 N
4. 30 N

Q29. Two forces F1 and F2 are acting on a particle. The particle will remain at rest if two forces are

1. Equal
2. Opposite
3. Equal and Opposite
4. Unequal and in same direction

Q30. A particle moves in a circle of radius 0.30m with a constant speed of 6m/s. Its centripetal acceleration is

1. 20 m/s2
2. zero
3. 120 m/s2
4. 12 m/s2

Q31. It is advised to drive along the slippery road slowly, because:

1. Friction is reduced
2. Normal reaction gets reduced
3. water on the road opposes the motion

Q32. A body in equilibrium:

1. has two equal forces acting in opposite directions
2. has zero resoltant of all the external forces acting on it.
3. has external forces balanced by internal forces
4. has zero resoltant of all internal forces but not of external ones

Q33. A lift of mass 1000kg , which is moving with an acceleration of 1 m/s2 in upward direction has tension developed in its string equal to:

1. 9800 N
2. 10800 N
3. 11000 N
4. 10000 N

Q34. A body of mass 2kg is hung from a spring balance which is hung vertically in a lift. If the lift falls downward with an acceleration of 9.8m/s2, then reading of the spring balance is

1. zero
2. more than 2 kg
3. less than 2 kg but not zero
4. 0.2 kg

Q35. An average force of 100N acts on a body to create an acceleration of 1 m/s2 . What is the mass of the body?

1. 0.1 kg
2. 10 kg
3. 100 kg
4. 100000 kg

Q36. If no resoltant force acts on a body then the body will be in

1. rest
2. motion
3. earlier state (no change in state)
4. none of the above

Q37. The product of forceand the duration of time for which it acts on a body is equal to the

1. rate of change of momentum
2. change of momentum
3. rate of change of acceleration
4. change of acceleration

Q38. Another name for the first law of motion is

1. Law of gravitation
2. Law of conservation of energy
3. Law of inertia
4. Law of conservation of energy

Q39. The property of a body due to which it resists any change in its state of rest or of uniform motion is called its:

1. Mass
2.     Moment of inertia
3. Inertia
4. Weight

Q40. At which place of the earth, the centripetal force is maximum

1. At the north pole
2. At the south pole
3. At the equator
4. At the earth surface