Advertisements
Advertisements
प्रश्न
Explain conservation of energy.
Advertisements
उत्तर
Energy cannot be created cannot be destroyed also. It is changed from one form to another form or transferred from one object to another object. Examples for conservation of energy in our daily life are:
-
Water dam:
a. Water stored in water dams possesses potential energy.
b. When water falls down, the potential energy of water is converted, into kinetic energy.
c. Kinetic energy of water rotates the turbines and electric energy is generated. - Electrical appliances:
a. Electrical energy is used in many domestic appliances such as electric stoves, iron boxes, and fans.
b. Electric energy flows into the coil in the devices.
c. As the current flows, it heats up the coil.
d. With the help of this heat energy, we do many useful works.
e. Thus, electrical energy is converted into heat energy.
f. Electical energy is converted to mechanical energy in a fan, light energy in a bulb, and sound energy in a computer. - Driving a car:
a. We use fuel in the form of petrol or diesel or gas to run vehicles.
b. When this fuel burns in the engine, chemical energy is converted into heat energy.
c. Burning fuel produces hot gases which pushes the piston in the engine to move the vehicle.
d. Thus heat energy is converted into mechanical energy.
APPEARS IN
संबंधित प्रश्न
State the energy changes that occur in a watch spring while it unwinds.
State the energy changes in the following while in use A loudspeaker .
State the energy changes in the following while using an electric motor.
State the energy changes in the following case while in use:
A petrol engine of a running car
A metal ball of mass 2 kg is allowed to fall freely from rest from a height of 5 m above the ground. What happens to the mechanical energy after the ball hits the ground and comes to rest?
Avinash can run with a speed of 8 m s–1 against the frictional force of 10 N, and Kapil can move with a speed of 3 m s–1 against the frictional force of 25 N. Who is more powerful and why?
Can any object have mechanical energy even if its momentum is zero? Explain.
A light and a heavy object have the same momentum. Find out the ratio of their kinetic energies. Which one has larger kinetic energy?
Four men lift a 250 kg box to a height of 1 m and hold it without raising or lowering it.
(a) How much work is done by the men in lifting the box?
(b) How much work do they do in just holding it?
(c) Why do they get tired while holding it? (g = 10 m s–2)
In an electric cell while in use, the change in energy is from ______.
