A 40 kg child standing on a frozen pond throws a 0.5 kg stone to the east with a speed of 5 m/s. Negelcting friction between the child and the ice, what is the recoil velocity of the child?
A)5m/s west
B)5m/s east
C)0.0625m/s west
D)0.25m/s west
E)0.0125m/s east
Hint:
The initial momentum is zero, the total final momentum must also be zero.
Final momentum of the stone: p = 0.5kg*5m/s east = 2.5kgm/s east
The final momentum of the child must have the same magnitude and be in the opposite direction.
Final velocity of child = final momentum of child/mass of child