Question

Which is having more momentum:
A bullet of mass 10g moving with velocity 400m/s or a cricket ball of mass 400g moving with velocity 90km/h.​

Answer 1

In case of bullet

m = 10g = 0.01kg

v = 400m/s

P = mv = 0.01kg × 400m/s = 4kg m /s

In case of cricket ball

m = 400g = 0.4 kg

v = 90 km/h = 25 m/s

P = mv = 0.4 kg × 25m/s = 10 kg m/s

Therefore, the momentum of bullet is less than that of the ball

Answer 2

Let bullet A having

mass = 10g = 10/1000kg = 10^-2kg

velocity = 400m/s

momentum = mass * velocity

p = 400*10^-2 = 4kgm/s

Let bullet B having

mass = 400g = 400/1000kg = 0.4 kg

velocity = 90km/hr = 90*5/18 = 25m/s

momentum = 0.4*25 = 10gm/s

Now on comparing

p(A)/p(B) = 4/10 = 2/5 = 0.4

5*moment of A = 2*moment of B

so moment of A is 0.4 times smaller then B .