A body is initially at rest. It undergoes one-dimensional motion with constant acceleration. The power delivered to it at time t is proportional to

1

(a)

t^1/2

(b)

t

(c)

t^3/2

(d)

t²

A body is moving unidirectionally under the influence of a source of constant power. Its displacement in time t is proportional to

1

(a)

t^1/2

(b)

t

(c)

t^3/2

(d)

t²

The work done by all the forces (external and internal) on a system equals the change in

1

(a)

total energy

(b)

kinetic energy

(c)

potential energy

(d)

none of these

A heavy stone is thrown from a cliff of height h with a speed v. The stone will hit the ground with maximum speed if it is thrown

1

(a)

vertically downward

(b)

vertically upward

(c)

horizontally

(d)

the speed does not depend on the initial direction

Two bodies of masses m and 4 m are moving with equal kinetic energy. The ratio of their linear momenta is

1

(a)

1 : 4

(b)

4 : 1

(c)

1 : 2

(d)

1 : 1

How much work is done by mass M moving once around a horizontal circle of radius r?

1

(a)

In physics, circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform, with constant angular rate of rotation and constant speed, or non-uniform with a changing rate of rotation. The rotation around a fixed axis of a three-dimensional body involves circular motion of its parts. The equations of motion describe the movement of the center of mass of a body.

Does the work done in moving a body depend upon how fast the body is moved?

1

(a)

No that is not the case. Lets say a body is moving very fast but going with uniform motion so its acceleration will be zero and when acceleration is zero force is also zero so as a result W = 0
as W = F x d

Define spring constant of a spring. Give its SI unit.

1

(a)

Spring constant is defined as the restoring force per unit displacement. Thus, it is measured in Nm^–1.

Friction is a non-conservative force. Why?

1

(a)

Friction is a good example of a nonconservative force. Work done against friction depends on the length of the path between the starting and ending points. Because of this dependence on path, there is no potential energy associated with nonconservative forces.

What is the coefficient of restitution?

1

(a)

The value is almost always less than one due to initial translational kinetic energy being lost to rotational kinetic energy, plastic deformation, and heat. It can be more than 1 if there is an energy gain during the collision from a chemical reaction, a reduction in rotational energy, or another internal energy decrease that contributes to the post-collision velocity.
\(\text { Coefficient of restitution }(e)=\frac{\mid \text { Relative velocity after collision } \mid}{\mid \text { Relative velocity before collision } \mid}\)