EASY

Earn 100

An archer stretches the string of his bow to shoot an arrow. Name the type of energy into which it is converted.

Important Questions on Energy

MEDIUM

Science>Physics>Energy>Transformation of Energy

Name a machine that converts electrical energy into mechanical energy.

EASY

Science>Physics>Energy>Transformation of Energy

State the energy changes in the case of an electric iron while in use.

EASY

Science>Physics>Energy>Transformation of Energy

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

EASY

Science>Physics>Energy>Transformation of Energy

The potential energy of a system increases if work is done

EASY

Science>Physics>Energy>Transformation of Energy

In any physical or chemical process, the total energy:

EASY

Science>Physics>Energy>Transformation of Energy

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)
Question Image

HARD

Science>Physics>Energy>Transformation of Energy

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

EASY

Science>Physics>Energy>Transformation of Energy

Blocks of masses

m, 2 m, 4 m

and

8 m

are arranged in a line of a frictionless floor. Another block of mass

m

, moving with speed

υ

along the same line (see figure) collides with mass

m

in perfectly inelastic manner. All the subsequent collisions are also perfectly inelastic. By the time the last block of mass

8 m

starts moving the total energy loss is

p %

of the original energy. Value of

p

is close to:
Question Image

EASY

Science>Physics>Energy>Transformation of Energy

The temperature of the water at the bottom of a water fall is higher than that of the water at the top, because :

EASY

Science>Physics>Energy>Transformation of Energy

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

HARD

Science>Physics>Energy>Transformation of Energy

A particle is moving in a circle of radius

r

under the action of a force

F = α r^{2}

which is directed towards centre of the circle. Total mechanical energy (kinetic energy + potential energy) of the particle is (take potential energy

= 0

for

r = 0

EASY

Science>Physics>Energy>Transformation of Energy

An electric device which converts electric energy into mechanical energy is called

MEDIUM

Science>Physics>Energy>Transformation of Energy

A person trying to lose weight by burning fat lifts a mass of 10 kg upto a height of 1m 1000 times. Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up? Fat supplies

3.8 \times 10^{7}

J of energy per kg which is converted to mechanical energy with a 20% efficiency rate. Take

g = 9.8 m s^{- 2}

EASY

Science>Physics>Energy>Transformation of Energy

Describe in your words the law of conservation of energy.

EASY

Science>Physics>Energy>Transformation of Energy

Hydrogen ion and singly ionized helium atom are accelerated, from rest, through the same potential difference. The ratio of final speeds of hydrogen and helium ions is close to:

MEDIUM

Science>Physics>Energy>Transformation of Energy

A mass of $0.5 kg$ moving with a speed of $1.5 m s^{- 1}$ on a horizontal smooth surface, collides with a nearly weightless spring of force constant $k = 50 N m^{- 1}$ . The maximum compression of the spring would be