Explanation:
Momentum is mass times velocity.
p = mv
a) Before the bullet is shot, it has zero velocity. So p = 0 kg m/s.
b) Before the bullet is shot, the rifle has zero velocity. So p = 0 kg m/s.
c) The total momentum is therefore 0 + 0 = 0 kg m/s.
d) If m = 5 g = 0.005 kg, and v = 100 m/s, then:
p = (0.005 kg) (100 m/s) = 0.5 kg m/s
e) Momentum is conserved, so the total momentum before the bullet is shot equals the total momentum after the bullet is shot.
p = 0 kg m/s
f) Since the total momentum is 0:
0 kg m/s = 0.5 kg m/s + p
p = -0.5 kg m/s
g) If M = 995 g = 0.995 kg:
-0.5 kg m/s = (0.995 kg) vr
vr ≈ -0.503 m/s
