Question

Two objects having equal masses moving with velocities 10m/s and 60m/s
respectively. Which of these will possess maximum kinetic energy?

Answer 1

Body moving with velocity 60 m/s has maximum kinetic energy.

GIVEN :

• Velocity of first object is 10 m/s

• Velocity of second object is 60 m/s

• Let masses of both object are equal to m.

TO FIND:

Kinetic energy of both objects

FORMULA:

Kinetic energy , k = (mv²) / 2

SOLUTION:

STEP 1 : KINETIC ENERGY OF FIRST OBJECT

k = (mv²) / 2

k = (m × 10²) / 2

k = (100 × m) / 2

k = 50m joules

Kinetic energy of first object is 50m

STEP 2 : KINETIC ENERGY OF SECOND OBJECT

k = (mv²) / 2

k = (m × 60²) / 2

k = (3600 × m) / 2

k = 1300m joules

Kinetic energy of second body is 1300m

ANSWER:

• Kinetic energy of first body is 50m

• Kinetic energy of second body is 1300m

• By compairing the kinetic energies of first and second body , it is clear that the kinetic energy of second body is more.

• Hence the second body moving with velocity 60 m/s possesses maximum kinetic energy.

SHORT TRICK:

• When mass is constant and same for both objects, kinetic energy is directly proportional to the square of velocity.

• Since the second object moves with maximum velocity, it's kinetic energy will also be maximum.