A particle of mass m is initially at rest at the origin. It is subjected to a force and starts moving along the x - axis. Its kinetic energy changes with time as d K d t = γ t , where γ is a positive constant of appropriate dimensions. Which of the following statements is (are) true?

The distance of the particle from the origin increases linearly with time

EASY

Earn 100

Explain the energy transformation in a pole vault event.

Important Questions on Work, Power and Energy

HARD

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

A particle of mass

m

is initially at rest at the origin. It is subjected to a force and starts moving along the x - axis. Its kinetic energy changes with time as

\frac{d K}{d t} = γ t,

where

γ

is a positive constant of appropriate dimensions. Which of the following statements is (are) true?

EASY

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

Describe in your words the law of conservation of energy.

EASY

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

In a simple Pendulum the displacement is equal to amplitude. Then kinetic energy will be

EASY

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

Some of the following equations are kinematical equations, where the symbols have their usual meaning. The

w o r k - e n e r g y

theorem is represented by

HARD

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

Name the device that converts electrical energy into mechanical energy. Draw its diagram and label the parts.

MEDIUM

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

A body of mass

m = 10^{- 2} kg

is moving in a medium and experiences a frictional force

F = - k v^{2} .

Its initial speed is

v_{0} = 10 m s^{- 1} .

After

10 s

its kinetic energy is

\frac{1}{8} m v_{0}^{2},

then value of

k

will be:-

EASY

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

A marble P of mass m lies at rest on the edge of a perfectly horizontal surface of a table of height h, as shown in the figure. A second identical marble Q having same mass moving at a speed u strikes it perfectly elastically. The speed acquired by marble P after the collision is (In an elastic collision, momentum as well as kinetic energy are conserved)
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MEDIUM

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

A person of mass

M

is sitting on a swing of length

L

and swinging with an angular amplitude

θ_{0} .

If the person stands up when the swing passes through its lowest point, the work done by him, assuming that his centre of mass moves by a distance

l (l ≪ L),

is close to:

EASY

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

Which device is used to convert mechanical energy into electrical energy? Draw a neat diagram and label the parts of this device.

EASY

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

In any physical or chemical process, the total energy:

HARD

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

A point particle of mass m, moves along the uniformly rough track PQR as shown in the figure. The coefficient of friction, between the particle and the rough track equals

μ

. The particle is released, from rest, from the point P and it comes to rest at a point R. The energies, lost by the ball, over the parts, PQ and QR, of the track, are equal to each other, and no energy is lost when particle changes direction from PQ to QR.
The values of the coefficient of friction

μ

and the distance

x = (Q R)

, are respectively close to:

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EASY

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

State the energy changes in the case of a ceiling fan while in use.

HARD

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

A particle moves in one dimension from rest under the influence of a force that varies with the distance traveled by the particle as shown in the figure. The kinetic energy of the particle after it has traveled

3 m

is:

MEDIUM

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

A body of mass

m

starts moving from rest along

x -

axis so that its velocity varies as

v = a \sqrt{s}

where

a

is a constant and

s

is the distance covered by the body. The total work done by all the forces acting on the body in the first

t

second after the start of the motion is

HARD

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

A thin and uniform rod of mass

M

and length

L

is held vertical on a floor with large friction. The rod is released from rest so that it falls by rotating about its contact-point with the floor without slipping. Which of the following statement(s) is/are correct, when the rod makes an angle

60^{o}

with vertical?
[

g

is the acceleration due to gravity]

MEDIUM

Physics>Mechanics>Work, Power and Energy>Kinetic Energy and Work Energy Theorem

In the diagram below the spring has a force constant of $K$ , the block has a mass of $m$ , and the height of hill is $h$ . Determine the compression of the spring $x$ such that the block just reaches to the top of the hill.
(Assume that there are no non-conservative forces involved.)

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