An athlete at the gym holds a 2.5 kg steel ball in his hand. His arm is 70 cm long and has a mass of 4.0 kg. a) What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor?
b) What is the magnitude of the torque about his shoulder if he holds his arm straight, but 55? below horizontal?

You are driving to the grocery store at 20 m/s. you are 110m from an intersection when the traffic light turns red. assume that your reaction time is 0.50s and that your car brakes with constant acceleration. how far are you from the intersection when you begin to apply the brakes? what acceleration will bring you to rest right at the intersection? how long does it take you to stop after the light changes? the known values: vi=20m/s xi=110m t=.50s vf=0m/s xf=0m a=?