VBQs Work Energy and Power Class 11 Physics with solutions has been provided below for standard students. We have provided chapter wise VBQ for Class 11 Physics with solutions. The following Work Energy and Power Class 11 Physics value based questions with answers will come in your exams. Students should understand the concepts and learn the solved cased based VBQs provided below. This will help you to get better marks in class 11 examinations.

**Work Energy and Power VBQs Class 11 Physics**

**Question. The potential energy U of a diatomic molecule varies with interatomic separation r as U = a/r12 – b/r6, where a and b are positive constants. Find the interatomic separation for which atoms are in equilibrium**

(a) Zero

(b) (b/2a)1/6

(c) (2a/b)1/6

(d) (a/b)1/6

## Answer

C

**Question. A ball of mass 500 gm moving with speed 2 m/s collide to a floor making an angle of 45° with vertical.**

If coefficient of restitution is 1/√3 , then the angle made by the ball with normal, after collision is

(a) 60°

(b) 30°

(c) 45°

(d) 37°

## Answer

B

**Question. A ball is dropped from a height h = 10 m on the ground.**

If the coefficient of restitution is e, the height to which the ball goes up after it rebounds for the nth time is

(a) e^{2n}/10 m

(b) 10e^{2n} m

(c) ne^{10} m

(d) 10e^{n} m

## Answer

B

**Question. A bullet loses 1/n th of its velocity passing through one plank. How many such planks are required to stop the bullet?**

(a) (2n–1/n^{2})

(b) (n/n–1)

(c) (n^{2}/2n–1)

(d) (n–1 /n)

## Answer

C

**Question. A body A of mass m elastically collides with another identical body B as shown in figure. The velocity of body A after collision is **

(a) v̅

(b) v̅/2

(c) Zero

(d) v̅/3

## Answer

C

**Question. A stone is tied to a string of length l and is moving in vertical circle such that the tension in the string at the highest position of stone is zero. Find the angle θ of string with lowest position when tension in the string is equal to the weight of stone **

(a) cos^{–1} (1/3)

(b) cos^{–1} (2/3)

(c) cos^{–1} (–2/3)

(d) sin^{–1} (1/3)

## Answer

C

**Question. Work done against spring force in increasing the extension in a spring from x1 to x2 is (spring constant is k)**

(a) 1/2 k(x_{2}–x_{1})^{2}

(b) 1/2 k(x_{2}–x_{1} /2)^{2}

(c) 1/2 k(x_{2}–x_{1}) (x_{2}+x_{1})^{2}

(d) 1/2 k(x_{1}^{2}–x_{2}^{2})

## Answer

C

**Question. A block of mass m is lowered vertically by a distance d with constant acceleration g/4 by means of a light inextensible string. Work done on the block by gravity is**

(a) mgd /4

(b) 3mgd /4

(c) -3mgd/4

(d) mgd

## Answer

D

**Question. A stationary body explodes into two pieces of masse 6 kg and 4 kg, which move in opposite directions. The ratio of their kinetic energies E1/E2 is**

(a) 3/2

(b) 13/2

(c) 2/3

(d) 2/13

## Answer

C

**Question. A bomb at rest explodes into two fragments of masses 3 kg and 1 kg. The ratio of magnitude of velocities of the smaller and bigger fragment is**

(a) 3

(b) 1

(c) 1/2

(d) 1/3

## Answer

A

**Question. A body of mass m is lifted up from the earth surface to a height R above the earth’s surface without changing its kinetic energy. The work done in this process is equal to**

(a) Zero by the resultant force acting on the body

(b) mgR/2 by the applied force acting on the body

(c) –mgR/2 by the applied force acting on the body

(d) All of these

## Answer

D

**Question. A body of mass m initially at rest starts moving and attains a velocity A in time T. Then, what **

## Answer

A

**Question. A particle is moving in a region, where its potential energy U varies with co-ordinates x, y and z as **

## Answer

A

**Question. A knife having mass m is dropped from a height h above the surface of earth. If the knife penetrates upto distance x in the soil. The average force applied by the soil is **

## Answer

A

**Question. A bullet of mass m is moving with speed u hits a stationary wooden block of mass M placed on a smooth surface and gets embedded into it, then the percentage loss of energy during collision is **

## Answer

A

**Question. A radioactive nucleus of mass number A initially at rest emits an α-particle having kinetic energy K. The KE of recoiling nucleus will be**

(a) K

(b) K/A-4

(c) 4K/A-4

(d) K/4

## Answer

C

**Question. If a small particle of mass m is released from horizontal position as shown. (c is centre of circular path). Then the maximum tension in thread will be**

(a) mg

(b) 2mg

(c) 3mg

(d) 4mg

## Answer

C

**Question. The blocks shown in figure are identical and each has mass 2 kg. If block A moving with speed 4 m/s collides with B and collision is perfectly elastic then the maximum compression produced in spring will be [spring constant k = 100 N/m] **

(a) 0.4 m

(b) 0.8 m

(c) 1.2 m

(d) 1.6 m

## Answer

A

**Question. A ball moving with velocity = 6 m/s perpendicular to a wall collides with it. Magnitude of change in velocity of ball the due to collision is (Assuming coefficient of restitution = 1/3) **

(a) 2 m/s

(b) 6 m/s

(c) 9 m/s

(d) 8 m/s

## Answer

D

**Question. A body of mass m moving with a constant velocity v hits another body of the same mass moving with the same speed v in the opposite direction and sticks to it. The speed of the compound body after collision is**

(a) v 2

(b) 2v

(c) v/2

(d) Zero

## Answer

D

**Question. If coefficient of restitution between ball and ground is e, then find speed of ball just after collision **

## Answer

D

**Question. A ball is dropped from height 32 cm above ground level. If the coefficient of restitution between the ball and ground is 0.5 then, to what height will it rise after first collision?**

(a) 16 m

(b) 8 m

(c) 4 m

(d) 0.8 m

## Answer

D

**Question. A bullet of mass m moving horizontally with velocity v is fired into a large wooden block of mass M kept at rest on a smooth horizontal surface. The magnitude of final velocity of this bullet-block system is**

(a) (m+M)v/m

(b) (m+M)v/M

(c) (mv)M+m

(d) (M–m)v /m

## Answer

C

**Question. A body of mass (m) moving with speed v compresses a spring of spring constant(K). Maximum compression in spring is given by **

## Answer

B

**Question. A block moving with speed V starts compressing a spring of spring constant k as shown in figure. The compression in spring when speed of block becomes V/2 is **

## Answer

B

**Question. A ball of mass 10 kg is moving with velocity 10 m/s strikes the bob of a pendulum at rest. The mass of the bob is also 10 kg. If the collision is perfectly inelastic, then the height to which the combination of two will rise is**

(a) 2 m

(b) 1.6 m

(c) 1 m

(d) 1.25 m

## Answer

D