Energy Example Problems
1) Goliath (the roller coaster) at Magic Mountain is reportedly 255 feet tall = 77 meters tall. How fast (theoretically) are you moving at the bottom of the first drop? (they say 85mpg) How fast are you going at the top of the next hill which is 20 meters above the bottom?
2) Rosanna Anna Danna is changing the tire of her car on a steep hill 20.0 m high. She trips (face plants) and drops the 10kg spare tire, which rolls down the hill with an initial speed of 2 m/s. What is the speed of the tire at the top of the next hill (where it runs over the tail of Mr.D’s cat) , which is 5m high?
3) You’re holding a 5 gram grasshopper in your hand. The grasshopper jumps and you estimate it traveled 15cm straight up.
- How much Potential energy has it gained?
- With what speed did the grasshopper jump from your hand?
Energy Problems with friction (loss of energy due to Work)
1) A 70kg snowboarder does her “powerslide” into the unsuspecting group of boarders waiting at Chair 3. The coefficient of friction between the board and the rough snow is 0.7. She slides so that her speed is zero after she sprays the motley crowd. How far did she slide? (use energy/work ideas)