Question

a 4kg mass and 1kg mass are moving with equal kinetic energies.what is the ratio of their momnenta?

Answer 1

kinetic energy = 1/2 * mass * velocity ^2
1/2 * 4 * velocity 1^2 = 1/2 * 1 * velocity 2^2
so the velocity of 1 kg mass is twice than velocity of 4 kg mass
velocity 2=2 velocity 1
momentum = mass * velocity
momentum 1 = 4 * v
momentum 2=1 * 2
ratio = 4v: 2v

Answer 2

We have,

m1 = 4kg
m2 = 1kg

Also,
v1 = v2

Now,

KE of M1 = 1/2 x m1 x v ^2

KE of M2 = 1/2 x m2 x v^2

Now,

A/Q,

Ke of M1 /Ke of M2

= m1 /m2

= 4 /1

Hence, reaction of their KE = 4:1