Two people are standing on a 2.50-m-long platform, one at each end. The platform floats parallel to the ground on a cushion of air, like a hovercraft. The two people, the platform and a 3.63-kg ball are all initially at rest. One person throws the 3.63-kg ball to the other, who catches it. The ball travels nearly horizontally. Excluding the ball, the total mass of the platform and people is 198 kg. Because of the throw, this 198-kg mass recoils. How far does the platform move before coming to rest again?

The platform move before coming to rest again 0.045 m far

Explanation:

Given

Ball is in motion

M (Platform mass + 2 people mass)

V (recoil velocity of the platform)

m (ball mass)

v (velocity ball)

MV + mv = 0

Distance of the platform movement is

t (time that the ball is in the air)

x = Vt

t =

Knowing the platform and the ball are moving while the ball is in the air

x =

Also knowing that

This way,

x = =

The minus sign means the displacement of the platform is in opposite direction to the displacement of the ball.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

a skateboard rolling across the street - apex