Aman with mass 70.0 kg stands on a platform withmass 25.0 kg. he pulls on the free end of a rope thatruns over a pulley on the ceiling and has its other end fastened tothe platform. the mass of the rope and the mass of the pulley canbe neglected, and the pulley is frictionless. the rope is verticalon either side of the pulley.
a) with what force does he have to pull so that he and theplatform have an upward acceleration of 1.80\; {\rm m}/{\rm s}^{2}?
b) what is the acceleration of the rope relative to him?

Amass m = 74 kg slides on a frictionless track that has a drop, followed by a loop-the-loop with radius r = 18.4 m and finally a flat straight section at the same height as the center of the loop (18.4 m off the ground). since the mass would not make it around the loop if released from the height of the top of the loop (do you know why? ) it must be released above the top of the loop-the-loop height. (assume the mass never leaves the smooth track at any point on its path.) 1. what is the minimum speed the block must have at the top of the loop to make it around the loop-the-loop without leaving the track? 2. what height above the ground must the mass begin to make it around the loop-the-loop? 3. if the mass has just enough speed to make it around the loop without leaving the track, what will its speed be at the bottom of the loop? 4. if the mass has just enough speed to make it around the loop without leaving the track, what is its speed at the final flat level (18.4 m off the ground)? 5. now a spring with spring constant k = 15600 n/m is used on the final flat surface to stop the mass. how far does the spring compress?