Question

A 3 kg cat sitting on a 1.5 kg piece of cardboard on a frozen lake wants to jump to shore without touching the ice. If there is no friction between the cardboard and the ice, when the cat jumps. the cardboard will move in the opposite direction with a velocity:

A. half as great as the cat's velocity. B. equal to the cat's velocity.
C. twice as great as the cat's velocity. D. four times as great as the cat's velocity

Answer 1

initial momentum = 0
so
final momentum = 0

0 = 3*Vcat + 1.5*Vcardboard
so
Vcardboard = 3 Vcat/1.5 = 2 Vcat

Answer 2

actually speed rather than velocity because directions are opposite.