Imagine that a primate has a forearm length (L) of 0.3 m. The primate lifts a 5 kg weight from an elevation angle, (relative to horizontal) of 0 degrees to an angle of 30 degrees. how much WORK must the primate do to lift the weight?

Imagine that a 60 kg person eats a hamburger with 500 Calories (500 kcals) of energy. The person wants to completely metabolize the hamburger by walking up an endless flight of stairs. Each stair is 18 cm tall, and assume the mechanical efficiency of muscles during stair climbing is 25%. How many stairs would the person need to climb to metabolize the hamburger?