Answer:
20.4 cm/s
Explanation:
From the law of conservation of momentum,
mu+m'u' = mv+m'v' ................ Equation 1
Where m = mass of the first marble, m' = mass of the second marble, u = Initial velocity of the first marble, u' = initial velocity of the second marble, v = final velocity of the first marble, v' = Final velocity of the second marble.
make v the subject of the formula
v = (mu+m'u'-m'v')/m ............ Equation 2
Given: m = 20 g, u = 28 cm/s, m' =19 g, u' = 16 cm/s, v' = 24.3 cm/s.
Substitute into equation 2
v = [(20×28)+(19×16)-(19×24.3)]/20
v = (560+304-456)/20
v = 20.4 cm/s.
Hence the final velocity of the 20 g marble = 20.4 cm/s