Aball is spinning in a vertical circle at the end of a string that is 2.0m long. if the ball has a mass of 3.5kg and moves at a constant speed of 8.0 m/s, determine the tension in the string when the ball is at the top and bottom of the loop.

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.