Assignment:
Question 1. Jane, a 120 lb woman, trips while walking down the street. She stumbles forward and falls onto her outstretched right hand. At the instant Jane's hand contacts the ground her whole body is moving downward at a velocity of 9 m/s and has a downward acceleration of 9.8 m/s2 (gravity). Her body rapidly decelerates after contacting the ground; after 0.04 seconds it has stopped moving.
Assuming that Jane's entire body mass is halted in 0.04 seconds, how much force did Jane's hand experience? (Hint: F=ma)
Question 2. When Jane hit the ground with her hands, her wrist was extended at 45° and her elbow was bent at 45°. The length of her forearm is 27 cm and her upper arm is 32 cm.
Assuming the ground reaction force is acting directly vertically, what is the moment about Jane's elbow?
Question 3. What assumptions can one make when answering questions 1 and 2?