Question

(a) Define the term 'energy' of a body. What is the SI unit of energy.

(b) What are the various forms of energy ?

(c) Two bodies having equal masses are moving with uniform speeds of v and 2v respectively. Find the ratio of their kinetic energies.

Answer 1

a)Energy can be defined as the ability to do work. The amount of energy possessed by a body is equal to the amount of work it do when its energy is released.Energy is a scalar qauntity.
The SI unit of energy is Joule.
The energy required to do 1 joule of work is called 1 joule energy
b)There are many forms of energy

they are

1) solar energy

2) hydral energy

3) thermal energy

4) mechanical energy

5) kinetic energy

6) potential energy

7) light energy

8) wind energy

9) sound energy

10) heat energy

11) chemical energy

12) nuclear energy

13) electrical energy

14) heat energy
c)et two bodies of masses ,
body x = m
body y = m ( because they are equal in mass )
given .
body x = v
body y = 2v
k.e. of x = $\frac{1}{2}m{v}^2$
k.e. of y = $\frac{1}{2}m(2v{)}^2$

= $\frac{KEofx}{KEofy}$= $\frac{\frac{m{v}^2}{2}}{2m{v}^2}$

Therfore, ratio = 1/4 = 1 : 4