Three kids are riding on a snow sled traveling horizontally without friction at 19.8 m/s. The masses of Kid A, B, and C are 42.8 kg, 31.5 kg, and 25.9 kg, respectively.

What is the new velocity of the sled if Kid A jumps off vertically from the sled? (Kid A velocity = 0)

vf = 34.5 [m/s]

Explanation:

This problem considers the study of the conservation of the linear moment, momentum can be calculated using its definition.

p = m * v

where:

p = momentum [kg*m/s]

m = mass [kg]

v = velocity [m/s]

Since the moment is conserved, i. e. the momentum at the beginning of the action will be equal to the moment at the end of the movement

The initial mass is the sum of the masses of all children and the speed will be given in the initial conditions.

When the kid A jumps at a speed of zero, only we have the masses of children B & C. In this way we can determine their velocities at the end.

(42.8+31.5+25.9) * (19.8) = (42.8*0) + (31.5+25.9) * vf

vf = 34.5 [m/s]