Concept #1: Work Done by Gravity
Practice: You push on 3 kg box against a wall for a distance of 2 m with a 100-N force that makes 53° with the horizontal, as shown. The box-wall coefficient of friction is 0.3. Calculate the work done by:
Practice: A 70 kg person hikes from the bottom to the top of a 1,000 m hill with varying speeds. The path you take is very irregular, with varying inclinations. How much total work does gravity do on you during the entire hike?
Concept #2: Work on Inclined Planes
Practice: You push a 2-kg box from the bottom of an inclined plane with 50 N for 10 m. The incline makes 37° with the horizontal, and the box-incline coefficient of friction is 0.6. Find the work done by:
(b) friction, and
Example #1: Work on Inclined Planes