Work, Energy and Power Test

Result

Work, Energy and Power Test - 18

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Question 1
1 / -0

Work done by gravitational force on a man, in lifting a bucket out of the well by rope tied to the bucket is

A
negative

B
positive

C
zero

D
infinity

Solution

When the man pulls the bucket outside the well the gravitational potential of the man + bucket system increases and hence the work done by the gravitational force is negative.
Question 2
1 / -0

For a conservative force, F is equal to

A

B

C

D

Solution

Potential energy at a point is defined in terms the amount of work done, which is defined in terms of force and thus we get potential as an integral of force applied over some position x. Hence F(x) = -dU(x) / dx which is the differentiation of potential energy wrt position.
Question 3
1 / -0

Work done in motion of the body over a closed loop for conservative forces is

A
infintesimal

B
non-zero

C
zero

D
infinity
Question 4
1 / -0

The conservative frictional force always acts ____________ to the surface of the application of the friction.

A
Tangential

B
Perpendicular

C
Parallel

D
Normal

Solution

The friction is the phenomena that defines that there is a resistance which is present there between the two surfaces. This friction is applied tangentially to the surfaces in contact. Thus the main thing is that the forces on both of the surfaces act tangential to each other.
Question 5
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Work done by or against a conservative force in a round trip is

A
zero

B
minimum

C
maximum

D
may be maximum or zero

Solution

A conservative force is a force with the property that the total work done in moving a particle between two points is independent of the taken path. Equivalently, if a particle travels in a closed loop, the total work done (the sum of the force acting along the path multiplied by the displacement) by a conservative force is zero.
Question 6
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Select the odd one out

A
Viscous force

B
Frictional force

C
Electrostatic force

D
Air-resistance

Solution

Frictional force, Air-resistance, viscous force all these forces work against each other i.e., they are opposing forces, while electrostatic force is not a opposing force.
Question 7
1 / -0

A force which does not depend on the path taken to increase the potential energy is

A
Viscous force

B
Frictional force

C
Conservative force

D
Non - Conservative force

Solution

A force is said to be conservative if the work done by or against the force on a body is independent of path followed by the body and depends only on initial and final positions.
Work done by or against the conservative force in moving a particle along a closed path is zero.
Hence C is correct.
Question 8
1 / -0

Which of the following is not conserved in inelastic collision?

A
momentum

B
kinetic energy

C
both momentum and kinetic energy

D
neither momentum nor kinetic energ

Solution

In an inelastic collision, the force of reformation is not equal to the force of deformation and thus some amount of energy is lost. But still as no external force acts upon the system momentum is still conserved.
Question 9
1 / -0

When conservative force does positive work on a body, the potential energy of the body:

A
increases

B
decreases

C
remains unaltered

D
there is no relationship between force and potential energy

Solution

We have a relation between potential energy and work done:
The negative sign just shows the inverse relation between potential energy and work done by conservative force.
Question 10
1 / -0

Which of the following statement is not related to conservative force?

A
Work done in closed path is zero

B
Work done is recoverable

C
Path independent

D
Path dependent

Solution

A force is said to be conservative if the work done by or against the force on a body is independent of path followed by the body and depends only on initial and final positions.
Work done by or against the conservative force in moving a particle along a closed path is zero.