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Question (11)

QN0035139

A force acts on a particle in such a way that the position of the particle as a function of time is given by , where is in metres and is in seconds. The work done during the first 4 seconds is

(A)
(B)
(C)
(D)

Correct Answer: A

Explanation:

Acceleration

Acceleration after

Displacement in

Work Force displacement

Mass acc. disp.

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Question (12)

QN0035140

A cord is used to lower vertically a block of mass , a distance at a constant downward acceleration of . The work done by the cord on the block is

(A)
(B)
(C)
(D)

Correct Answer: C

Explanation:

As the cord is trying to hold the motion of the block, work done by the cord is negative.

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Question (13)

QN0035141

If a motorcyclist skids and stops after covering a distance of . The stopping force acting on the motorcycle by the road is , then the work done by the motorcycle on the road is

(A)
(B)
(C)
(D)
Zero

Correct Answer: D

Explanation:

Though an equal and opposite force acts on the road but since road does not undergo. any displacement, hence no work is done on the road.

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Question (14)

QN0035142

A ball moves in a frictionless inclined table without slipping. The work done by the table surface on the ball is

(A)
positive
(B)
negative
(C)
zero
(D)
None of these

Correct Answer: C

Explanation:

Motion without slipping implies pure rolling. During pure rolling work done by friction force is zero.

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Question (15)

QN0035143

A uniform force of newton acts on a particle of mass . The particle is displaced from position meter to position meter. The work done by the force on the particle is

(A)
(B)
(C)
(D)

Correct Answer: D

Explanation:

Given :

or

So work done by the given force

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Question (16)

QN0035144

A boy pushes a toy box along the floor by means of a force of directed downward at an angle of to the horizontal. The work done by the boy is

(A)
(B)
(C)
(D)

Correct Answer: C

Explanation:

.

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Question (17)

QN0035145

A body moves a distance of along a straight line under the action of a force of 5 newtons. If the work done is 25 joules, the angle which the force makes with the direction of motion of body is

(A)
(B)
(C)
(D)

Correct Answer: C

Explanation:

.

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Question (18)

QN0035146

Let be any vector. Another vector , which is normal to can be expressed as

(A)
(B)
(C)
(D)

Correct Answer: C

Explanation:

The dot product should be zero.

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Question (19)

QN0035147

If and then cosine of angle between and is

(A)
(B)
(C)
(D)

Correct Answer: B

Explanation:

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Question (20)

QN0035148

A particle moves from position to due to a uniform force of . If the displacement is in metre then work done will be

(A)
(B)
(C)
(D)
0

Correct Answer: C

Explanation:

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Question (11)

A force acts on a particle in such a way that the position of the particle as a function of time is given by , where is in metres and is in seconds. The work done during the first 4 seconds is

Explanation:

Link:

Question (12)

A cord is used to lower vertically a block of mass , a distance at a constant downward acceleration of . The work done by the cord on the block is

Explanation:

Link:

Question (13)

If a motorcyclist skids and stops after covering a distance of . The stopping force acting on the motorcycle by the road is , then the work done by the motorcycle on the road is

Explanation:

Link:

Question (14)

A ball moves in a frictionless inclined table without slipping. The work done by the table surface on the ball is

Explanation:

Link:

Question (15)

A uniform force of newton acts on a particle of mass . The particle is displaced from position meter to position meter. The work done by the force on the particle is

Explanation:

Link:

Question (16)

A boy pushes a toy box along the floor by means of a force of directed downward at an angle of to the horizontal. The work done by the boy is

Explanation:

Link:

Question (17)

A body moves a distance of along a straight line under the action of a force of 5 newtons. If the work done is 25 joules, the angle which the force makes with the direction of motion of body is

Explanation:

Link:

Question (18)

Let be any vector. Another vector , which is normal to can be expressed as

Explanation:

Link:

Question (19)

If and then cosine of angle between and is

Explanation:

Link:

Question (20)

A particle moves from position to due to a uniform force of . If the displacement is in metre then work done will be

Explanation:

Link:

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