john wants to get his friend, peter, to a height of 2.8 m above the ground to reach an apple in a tree. they connect a swing to a high branch in an adjacent tree. the bottom of the swing, X, is at a height of 1.2 m. peter has s mass of 45 kg. ignore the effects of any frictional forces.

Question

john wants to get his friend, peter, to a height of 2.8 m above the ground to reach an apple in a tree. they connect a swing to a high branch in an adjacent tree. the bottom of the swing, X, is at a height of 1.2 m. peter has  s mass of 45 kg. ignore the effects of any frictional forces.

calculate the minimum speed with which John needs to push peter from point X to reach the apple on the tree.
.................good luck.................

bobpursley · Answer

If the bottom of the swing is 1.2 meters, then his arms should easily reach up one more meter. That means the swing has to go .4 meters higher. 1/2 m v^2=mgh v^2=2g(1.2)=2.4g v= sqrt (of that).