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Q1. A man weighs 70 kg. He stands on a weighing scale in a lift which is moving upwards with an acceleration of 5ms².What would be the reading on the scale? (g=10 ms²).

• 220N
• 1050 N
• 1200 N
• 1000 N

Solution

R-mg = ma R = mg+ma = 70x15=1050N    

Q2. A force of 20 N is applied on a body of mass 4 kg kept on a rough surface having coefficient of friction 0.1. Find acceleration of body. Take g = 10 m/s²

• 6 m/s²
• 7 m/s²
• 4 m/s²
• 9 m/s²

Solution

   

Q3. Which of the following cannot be regarded as yet another kind of force?

• gravitational force
• electrostatic force
• magnetic force
• centripetal force

Solution

Centripetal force cannot be regarded as a kind of force as it arises due to other type of forces. Example: 1) It arises due to gravitational force in case of heavenly bodies. 2) It arises due to electrostatic force in case of electrons revolving around nucleus.

Q4. The product of mass and velocity is known as

• acceleration
• impulse
• momentum
• torque

Solution

Momentum = Mass x Velocity

Q5. Weight and normal reaction forces

• are both contact forces
• constitute action reaction forces
• always act opposite to each other.
• act through the centre of gravity of the body

Solution

Weight and normal reaction forces act through the centre of gravity of the body.  

Q6. The angle through which the outer edge is raised above the inner edge is called

• angle of repose
• angle of banking
• angle of inclination
• angle of declination

Solution

The angle through which the outer edge is raised above the inner edge is called angle of banking.

Q7. Spring force is a restoring force.

•     True
•     False
•     can’t predict
•     none of the above

Solution

True; Spring force is a restoring force.  

Q8. 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?

• Zero degree  
• Ninty degree  
• Hundred eighty degrees
• Forty five degree  

Solution

Hundred eighty degrees and this is because the book and the table act opposite to each other.

Q9. The contact forces of mechanics are fundamentally derived from

• Gravitational forces
• Viscous forces
• Friction
• Electrical forces

Solution

At the microscopic level, all bodies are made of charged constituents (nuclei and electrons) and the various contact forces arising due to elasticity of bodies, molecular collisions and impacts, etc. can ultimately be traced to the electrical forces between the charged constituents of different bodies.

Q10. The product of forceand the duration of time for which it acts on a body is equal to the

• rate of change of momentum
• change of momentum
• rate of change of acceleration
• change of acceleration

Solution

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

Q11. Which law says that every force is accompanied by an equal and opposite force?

• Newton's first law of motion
• Newton's second law of motion
• Newton's third law of motion
• law of inertia

Solution

Newton's third law of motion says that every force is accompanied by an equal and opposite force.

Q12. There are two bodies of masses m₁ and m₂ (m₁> m₂) moving with velocity v. If p₁ and p₂ are their momentum respectively, then, which of the following is correct?

• p₁ > p₂
• p₁ < p₂
• p₁= p₂
• None of these

Solution

p₁> p₂ ; momentum is the product of mass and velocity.

Q13. When a car moves on a banked road, the centripetal force is due to

• horizontal component of the normal force
• frictional force
• vertical component of the normal force and the frictional force
• horizontal component of the normal force and the frictional force

Solution

When a car moves on a banked road, the necessary centripetal force is provided by the horizontal component of normal reaction force and the frictional force .

Q14. When a wheel rolls on a level road, the direction of frictional force at the point of contact of wheel and ground is

• forward direction
• backward direction
• along the tangent to the wheel
• along the centre of the wheel

Solution

The point of contact basically moves backward that is why the frictional force will act in forward direction.

Q15. In which direction does friction act, when a block is moved up the inclined plane?

• Parallel to inclined plane
• Normal to inclined plane
• Parallel and in downward direction along the inclined plane
• Normal and in upward direction along the inclined plane

Solution

Force of friction acts parallel and in downward direction when the block is moved along the inclined plane in upward direction.

Q16. If no resultant force acts on a body then the body will be in

• rest
• motion
• earlier state (no change in state)  
• none of the above

Solution

If no resultant force acts on a body then the body will be in earlier state.

Q17. At the highest point, water does not fall out of the bucket when rotated in a vertical circle because

• weight provides the centripetal force
• weight provides the centrifugal force
• the coriolis force is equal to the weight
• the centrifugal force is equal to the weight

Solution

At the highest point, water does not fall out of the bucket rotated in a vertical circle, because weight provides the centripetal force.

Q18. 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 -

• F = mg + F sin θ
• F = mg - F sin θ
• F = F sin θ
• F = mg

Solution

From the figure, Reaction force is the sum of weight of the body and vertical component of the applied force pointed upward. F = mg + F sin θ

Q19. A block of mass 3 kg in contact with a second block of mass 2 kg rests on a horizontal frictionless surface . A horizontal force of 10 N is applied to push the first block. The force with which the first block pushes the second block is:

• 10 N
• 6 N
• 4 N
• 8 N

Solution

A = F /(m₁ +m₂) = 10/5 =2 m/s²Force on second block pushed by the first F = m₂a = 2x2 =4 N

Q20. A force which acts for a small time and also varies with time is called:

• Centripetal force
• Impulsive force
• Electrostatic force
• Electromagnetic force

Solution

A force which acts for a small time and also varies with time is called Impulsive force.

Q21. From the magnitude of impulse, it is possible to find the change in linear momentum because

• impulse < change in linear momentum
• impulse > change in linear momentum
• impulse = change in linear momentum
• impulse x time = change in linear momentum

Solution

From the magnitude of impulse, it is possible to find the change in linear momentum because impulse = change in linear momentum.

Q22. A cyclist bends while taking a sharp turn so that

• friction is reduced
• component of his weight provides centripetal force
• he can go fast
• it looks nice

Solution

This When the cyclist bends while taking a sharp turn, the component of his weight provides the necessary centripetal force and this reduces his dependence on friction alone to provide the centripetal force.

Q23. In mechanics, if the net external force on the particle is zero, then the particle is said to be in state of

• accelerated motion
• de-accelarated motion
• retarding motion
• equilibrium

Solution

If the net external force on the particle is zero, then the particle is said to be in equilibrium state.

Q24. Impending motion of a body is opposed by

• kinetic friction
• sliding friction
• static friction
• rolling friction

Solution

Impending motion of a body is opposed by static friction.

Q25. Which one of these quantities is not related with Newton's second law of motion?

• mass
• force
• length
• Acceleration

Solution

Newton's second law F = ma  

Q26. A particle moves in a circle of radius 0.30m with a constant speed of 6m/s. Its centripetal acceleration is

• 20 m/s²
• zero
• 120 m/s²
• 12 m/s²

Solution

a = v²/r = 36/0.30 = 120 m/s²

Q27. Two masses are in the ratio 5:1. What is ratio of their inertia?

• 25 : 1
• 1 : 25
• 5 : 1
• 1 : 5

Solution

Inertia is proportional to m² .

Q28. An ice cart of mass 60 kg rests on a horizontal snow patch with coefficient of static friction 1/3 . Assuming that there is no vertical acceleration , find the magnitude of maximum horizontal force required to move the ice cart.

• 100 N
• 110 N
• 209 N
• 196 N

Solution

 M = 60 kg , u = 1/3Maximum horizontal force required to move the cart = force of friction =uR                                                                                    =u mg =1 x 60 x (9.8 / 3)                                                                                    = 196 N

Q29. Which of the conditions shows that the particles are in equilibrium state for two forces F₁ and F₂ acting on the body?

• &nbspF₁ = -F₂
• F₁ = F₂
• 2F₁=F₂
• F₁= 2F₂

Solution

If the two forces acting on the particle are equal and apposite, then the particle is said to be in equilibrium state.

Q30. The inability of body to change its state of uniform motion or rest is known as

• Law of inertia
• Newton's third law of motion
• Newton's law of gravitation
• Newton's second law of motion

Solution

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

Q31. Passengers in a bus lean forward as bus suddenly stops. This is due to

• Inertia
• Change in speed
• Impulse
• Change in momentum

Solution

When bus suddenly stops, lower body of the passengers are in rest with the floor of the bus, whereas the upper part of their body continues to remain in motion due to inertia.

Q32. When a bull pulls a cart, the force that helps the bull to move forward is the force exerted by

• the cart on the bull
• the ground on the bull
• the ground on the cart
• the bull on the ground

Solution

The force that helps the bull to move forward is the force exerted by the ground on the bull.

Q33. Two masses are in the ratio 1:5. What is ratio of their inertia?

• 25 : 1
• 5 : 1
• 1 : 5  
• 1 : 25

Solution

Inertia is proportional to m²

Q34. Two forces F₁ and F₂ are acting on a particle. The particle will remain at rest if two forces are

• Equal
• Opposite
• Equal and Opposite
• Unequal and in same direction

Solution

Two forces F₁ and F₂ are acting on the particle. The particle will remain at rest if two forces are equal and opposite.

Q35. To maintain a body in uniform motion on a flat surface, we need to apply an external force to encounter the

• Centrifugal force
• Frictional force
• Gravitational force
• Centripetal force

Solution

To maintain a body in uniform motion on a flat surface, we need to apply an external force to encounter the frictional force.

Q36. If two ends of a spring balance are pulled by a force of 10N, then the reading of the spring balance will be

• 0 N
• 10 N
• 20 N
• 30 N

Solution

Spring balance works on action reaction principle. Hence, according to Newton's third law the force measured by Spring balance will be 10 N.

Q37. Ball bearings are used to convert :

• Static to dynamic friction
• limiting friction to dynamic friction
• sliding friction to rolling friction
• rolling friction to fluid friction

Solution

Ball bearings are used to convert the sliding friction to rolling friction.  

Q38. In which direction does the friction act, when a block is moved down the inclined plane?

• Parallel to inclined plane
• Normal to inclined plane
• Parallel and in upward direction along the inclined plane
• Normal and in upward direction along the inclined plane

Solution

When a block is moved down the inclined plane, the fictional force acts parallel and in upward direction along the inclined plane.

Q39. A mass of 100 kg is resting on a rough inclined plane of 60^o. If the coefficient of friction is 0.5, then the least force acting parallel to the plane to keep the mass in equilibrium is

• 603.7 N
• 605.5 N
• 500 N
• 100 N

Solution

  From the figure, the least force required to prevent the mass from the sliding down when the frictional force acts upward is .

Q40. Which law governs the phenomenon that a tablecloth is pulled out from under a setting of chinaware without damaging it?

• Newton’s third law  
• Newton’s first law
• Newton’s second law  
• Universal law of gravitation