Question

A bullet is of mass 'm' g and is moving with a velocity 'v' m/s. Find the kinetic energy of the bullet when
(a) The mass is doubled,
(b) The velocity is tripled.

Answer 1

K.E of the bullet = `1/2` mv²

(a) If the mass is doubled,

K.E' = `1/2`(2m) v²  = `2 xx 1/2`mv² = 2K.E

`"K.E"/"K.E" = 2/1`

(b) If the velocity is tripled, 

K.E = `1/2` m(3v)² = 9 x `1/2` mv²

`"K.E"/"K.E" = 9/1`