posted by monic .
A 2.1 103-kg car starts from rest at the top of a 5.9-m-long driveway that is inclined at 19° with the horizontal. If an average friction force of 4.0 103 N impedes the motion, find the speed of the car at the bottom of the driveway.
Hooke's law describes a certain light spring of unstretched length 32.0 cm. When one end is attached to the top of a door frame and a 5.40-kg object is hung from the other end, the length of the spring is 46.5 cm.
(a) Find its spring constant.
(b) The load and the spring are taken down. Two people pull in opposite directions on the ends of the spring, each with a force of 160 N. Find the length of the spring in this situation.