Car X is travelling at half the speed of car Y. Car X has twice the mass of car Y.
Which statement is correct?
A Car X has half the kinetic energy of car Y.
B Car X has one quarter of the kinetic energy of car Y.
C Car X has twice the kinetic energy of car Y.
D The two cars have the same kinetic energy.
Reference: Past Exam Paper – June 2004 Paper 1 Q17
Let the speed of car X = v. Speed of car Y = 2v
Let the mass of car X = 2m. Mass of car Y = m
Kinetic energy = ½ mv2
KE of car X = ½ (2m) v2 = mv2
KE of car Y = ½ (m) (2v)2 = 2 mv2