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This mock test of Work, Power And Energy MSQ for Physics helps you for every Physics entrance exam.
This contains 10 Multiple Choice Questions for Physics Work, Power And Energy MSQ (mcq) to study with solutions a complete question bank.
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*Multiple options can be correct

QUESTION: 1

One end of an unstretched vertical spring is attached to the ceiling and an object attached to the other end is slowly lowered to its equilibrium position. If * S* be gain in spring energy and

Solution:

(loss in *gravitationl potential energy*)

⇒ *G* = 2*S*

The correct answers are: ** S = G**,

*Multiple options can be correct

QUESTION: 2

A block of mass 2*kg* is hanging over a smooth and light pulley through a light string. The other end of the string is pulled by a constant force * F* = 40

Solution:

Free body diagram of block is as shown in figure.

From work-energy theorem

Work done by gravity is

and work done by tension is

The correct answers are: tension in the string is 40*N*, displacement of the block in the given interval of time is 2*m*, work done by tension is 80*J*

QUESTION: 3

For a particle moving on a straight line the variation of acceleration with time is given by the graph as shown initially the particle was at rest. Then the corresponding kinetic energy of the particle versus time graph will be :

Solution:

The above graphs show *v*-*t* graph from *a*-*t* graph and then *v*^{2}-*t* graph, which are self explanatory.

The correct answer is: D

*Multiple options can be correct

QUESTION: 4

The potential energy for a force field is given by U(*x*, *y*) = cos(*x* + *y*). The force is acting on a particle at position given by coordinates then which of the following statement is true.

Solution:

The correct answers are:

*Multiple options can be correct

QUESTION: 5

There are two massless springs *A* and *B* of spring constant *K _{A}* and

Solution:

If the springs are compressed to same amount :

If the springs are compressed by same force.

The correct answers are: If they are compressed to same distance, *W _{A}* >

*Multiple options can be correct

QUESTION: 6

Which of the following is/are conservative force(s)?

Solution:

Clearly for forces the integration do not require any information of the path taken.

Taking : *x*^{2} + *y*^{2} = *t*

2*xdx* + 2*ydy* = *dt*

which is solvable.

Hence are conservative forces.

But

requires some more information on path. Hence non-conservative.

The correct answers are:

*Multiple options can be correct

QUESTION: 7

The potential energy (in *J**oules*) of a particle of mass 1*kg* moving in a plane is given by ** V = 3x + 4y**, the position coordinates of the point being

Solution:

Let at time '*t*' particle crosses *y*-axis

⇒ Particle crosses *y*-axis at *y* = –4

At (6, 4) *U* = 34 & *KE* = 0

At (0, 4); *U* = –16

⇒ *KE* = 50

⇒ v = 10 m/s while crossing y-axis

The correct answers are: its acceleration is of magnitude 5*m*/*s*^{2}, its speed when it crosses the *y*-axis is 10*m/s*, it crosses the *y*-axis (*x* = 0) at *y* = –4

*Multiple options can be correct

QUESTION: 8

In the figure shown the potential energy * U* of a particle is plotted against its position

Solution:

x - x_{1} and x = x_{3} are not equilibrium positions because at these points. x = x_{2} is unstable, as * U* is maximum at this point.

The correct answers are: *x*_{1} is in stable equilibrium, *x*_{3} is in stable equilibrium, *x*_{2} is in unstable equilibrium

*Multiple options can be correct

QUESTION: 9

Work done by a force on an rigid object having no rotational motion will be zero, if :

Solution:

(a) If velocity and acceleration are not in same direction, work done by force perpendicular to acceleration will not be zero.

(b) If the object is at rest no force can do work

(c) If force is perpendicular to velocity work done will be zero

(d) If the point on the body has velocity component in direction of application of force work done will be non-zero.

The correct answers are: the object is at rest relative to ground but the point of application of force moves on the object, the force is always perpendicular to velocity of object

*Multiple options can be correct

QUESTION: 10

An engine can pull 4 coaches at a maximum speed of 20*m/s*. Mass of the engine is twice the mass of every coach. Assuming resistive force to be proportional to the weight. (Power of engine remains constant) :

Solution:

When 4 coaches (m each) are attached with engine (2*m*)

according to questions *P* = *K* 6mgv ...(1)

(constant power), (*K* being proportionality constant)

Since resistive force is proportional to weight

Now if 12 coaches are attached

...(2)

Since engine power is constant

So by equation (1) and (2)

Similarly for 6 coaches

The correct answers are: maximum speed of engine when it pulls 12 coaches is 8.5*m/s*, maximum speed of engine when it pulls 6 coaches is 15*m/s*

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