Newton Law of Motion HC Verma Solutions Concept of Physics Ch-5 Vol-1 for Class-11. Solution of Questions for short answer, Objective -1 (MCQ-1), Objective -2 (MCQ-2) and Exercise with Numericals. Step by step Solutions of HC Verma Class-11 Ch-5 Newton Law of Motion Volume- 1 (Concept of Physics). Visit official Website CISCE for detail information about ISC Board Class-11 Physics..

## Newton Law of Motion HC Verma Solutions Concept of Physics Ch-5 Vol-1 for Class-11

 Board ISC and other board Publications Bharti Bhawan Publishers Ch-5 Newton Law of Motion Class 11 Vol 1st writer H C Verma Book Name Concept of Physics Topics Solution of Questions for short answer Objective -1 (MCQ-1), Objective -2 (MCQ-2) and Exercise Page-Number 76 ,77,78,79,80,81,82,83

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Newton Law of Motion HC Verma Solutions Concept of Physics Ch-5 Vol-1 for Class-11

(page-76)

#### Question-1

The apparent weight of an object increases in an elevator while accelerating upward. A person sells peanuts using a beam balance in an elevator. Will he gain more if the elevator is accelerating up?

No, the accelerating elevator will affect the weight of both sides of the beam balance. So, the net effect of the accelerating elevator cancels out, and we get the actual mass.

#### Question-2

A boy puts a heavy box of mass M on his head and jumps from the top of a multi-storied building to the ground. What is the force exerted by the box on the boy’s head during his free fall? Does the force greatly increase during the period he balances himself after striking the ground?

During free fall:
Acceleration of the boy = Acceleration of mass M = g
Acceleration of mass M w.r.t. boy, a = 0
So, the force exerted by the box on the boy’s head = M × a = 0
Yes, the force greatly increases during the period he balances himself after striking the ground because of the weight of the box.

#### Question-3

A person drops a coin. Describe the path of the coin as seen by the person if he is in (a) a car moving at constant velocity and (b) in a free falling elevator.

(a) a car moving at constant velocity– In the car, the path of the coin will be vertically downward because the only force acting on the coin is gravity in the downward direction.

(b) in a free falling elevator.- the coin as well as the person will be in a condition of weightlessness. So, the coin will remain stationary with respect to the person

Because all fee falls objects weightlessness.

#### Question-4

Is it possible for a particle to describe a curved path if no force acts on it? Does your answer depend on the frame of reference chosen to view the particle?

If no force acts on the particle it cannot change its direction. So, it is not possible for a particle to describe a curved path if no force acts on it.
Yes, the answer depends on the frame of reference chosen to view the particle if the frame of reference describes a curved path.

#### Question-5

You are travelling in a car. The driver suddenly applies the brakes and you are pushed forward. Why does this happen?

We are pushed forward because of the inertia of motion, as our body opposes the sudden change

#### Question-6

It is sometimes heard that the inertial frame of reference is only an ideal concept and no such inertial frame actually exists. Comment.

We can’t find a body whose acceleration is zero with respect to all other bodies in the universe because every body in the universe is moving with respect to other bodies.As we live on earth which itself is accelerates due to its revolution around the sun and spinning about its own axis, so whatever observations and measurements ,we make , are w.r.t to earth which itself is not an inertial frame.Similarly all other planets are also in motion around the sun so ideally no inertial frame is possible.

#### Question-7

An object is placed far away from all the objects that can exert force on it. A frame of reference is constructed by taking the origin and axes fixed in this object. Will the frame be necessarily inertial?

Yes, if the force on the object is zero, its acceleration w.r.t. all the other objects will we zero. So, the frame will necessarily be an inertial frame.

#### Question-8

figure (5-Q.1) shows a light spring balance connected to two blocks of mass 20 kg each. The graduations in the balance measure the tension in the spring. (a) What is the reading of the balance? (b) Will the reading change if the balance is heavy, say 2.0 kg? (c) What will happen if the spring is light but the blocks have unequal masses? The reading of the balance = Tension in the string
And tension in the string = 20g
So, the reading of the balance = 20g = 200 N

(b) If the balance is heavy, the reading will not change because the weight of spring balance does not affect the tension in the string.

(c) If the blocks have unequal masses, the spring balance will accelerate towards the heavy block with an acceleration a. Then the reading will be equal to the tension in the string. Suppose m1 > m2.
Then tension in the string, ( Page-77 )

#### Question-9

The acceleration of a particle is zero, as measured from an inertial frame of reference. Can we conclude that no force acts on the particle?

No. The acceleration of the particle can also be zero if the vector sum of all the forces is zero, i.e. no net force acts on the particle.

#### Question-10

Suppose you are running fast in a field and suddenly find a snake in front of you. You stop quickly. Which force is responsible for your deceleration?

The force of friction acting between my feet and ground is responsible for my deceleration.

#### Question-11

If you jump barefoot on a hard surface, your legs are injured. But they are not injured if you jump on a soft surface like sand or pillow. explain

In both the cases, change in momentum is same but the time interval during which momentum changes to zero is less in the first case. So, by force in the first case will be more. That’s why we are injured when we jump barefoot on a hard surface.

#### Question-12

According to Newton’s third law, each team pulls the opposite team with equal force in a tug of war. Then, why does one team win and the other lose?