A 60kg woman does a step-up/step-down task using a 25cm platform. A full step cycle consists of a step-up a followed by a step-down. During each step-up assume she is lifting her entire mass with one leg. Ignoring accelerations and motion in the horizontal direction a. How many step-ups would the woman need to do to expend at least 1kCal of energy? b. How quickly (steps/min) would she need to do the activity if the goal was expend at least .05kCal/s? (assume step up and down time is the same)

A force is acting on a 2.00 kg particle whose position changes with time as x = 4.0 t² - (1/3) t³, with x in meters and t in seconds. 8. find the work done on the particle by the force from t = 0 tot 3.0 sec. b. 327 J a. 256 J c. 164 J d. 225 J

A car is moving with a kinetic energy of 80 J and is slowed down and stopped in a distance of 0.05 m. The friction force that stops the object is4 N.1600 N. 40 N.16000 N.160 N.

The maximum energy a bone can absorb without breaking is surprisingly small. For a healthy human of mass 60 kg, experimental data show that the leg bones of both legs can absorb about 200 J.a. From what maximum height could a person jump and land rigidly upright on both feet without breaking his legs? Assume that all the energy is absorbed in the leg bones in a rigid landing.b. People jump from much greater heights than this; explain how this is possible.Hint: Think about how people land when they jump from greater heights.