Question

A 14 kg rock starting from rest free falls through a distance of 5.0 m with no air resistance. Find the momentum change of the rock caused by its fall and the resulting change in the magnitude of earth’s velocity. Earth’s mass is 6.0 × 1024 kg. Show all your work, assuming the rock-earth system is closed.

Answer 1

v = sqrt (2 g h) = sqrt (2*9.8*5)
= 9.9 m/s

total momentum before = 0
total momentum after
= 14*9.9 - 6*10^24 v = 0

v = (14 * 9.9/6)*10^-24

Answer 2

So, let's go. Vf^2{squared final velocity}= Vi^2{squared initial velocity}+2a{acceleration}d{distance}. Acceleration is 9.8 for gravity, good luck my dudes.