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 is defined as the ability to do work and joule is the SI unit of energy. 

b) Following are the various forms of energy: 

Kinetic energy, potential energy, nuclear energy, electrical energy, chemical energy, sound energy, light energy, and heat energy. 

c) Let the mass of both the bodies be m 

Velocity of body 1, v₁ = v 

Velocity of body 2, v₂ = 2v

KE₁ = 1/2 mv² = 1/2 m(v₁) ² 

KE₂ = 1/2 mv² = 1/2 m(v^₂)² 

Ratio = KE₁ : KE₂ = 1/4