Q. A person doing a chin-up weighs 655 N exclusive of the arms. During the first 15.0 cm of the lift, each arm exerts an upward force of 355 N on the torso. If the upward movement starts from rest, what is the person's velocity at this point?
Q. A 1000 {rm kg} wrecking ball hangs from a 15 {rm m}-long cable. The ball is pulled back until the cable makes an angle of 25.0^circle with the vertical. By how much has the gravitational potential energy of the ball changed?