The kinetic energy of an object of mass, m moving with a velocity of 5 ms-1 is 25 J. What will be its kinetic energy when its velocity is doubled? What will be its kinetic energy when its velocity is increased three times?

Solution:

Given

K.E. of the object = 25J

Velocity of the object (v) = 5 m/s

K.E. = (½) mv²

25 = (½) m (5)²

50 = 25 x m

m = 50/25

m = 2 kg

Now, when velocity is doubled

v = 10 m/s

m = 2 kg

K.E. = (½) x 2 x (10)²

K.E. = 10²

K.E. = 100 J

When velocity is increased three times, then

v = 15 m/s

m = 2 kg

K.E. = (½) x 2 x (15)²

K.E. = (15)²

K.E. = 225 J