Bob (88 kg) jumps out of a plane, starting at rest. After falling for 1 km, he is moving downward at 96 m/s. How much work is done by friction over this distance? You may assume that the only forces are gravity and friction.

Suppose a force of 60 n is required to stretch and hold a spring 0.1 m from its equilibrium position. a. assuming the spring obeys hooke's law, find the spring constant k. b. how much work is required to compress the spring 0.5 m from its equilibrium position? c. how much work is required to stretch the spring 0.6 m from its equilibrium position? d. how much additional work is required to stretch the spring 0.1 m if it has already been stretched 0.1 m from its equilibrium? a. kequals 600