Grade 8 Energy Summative Review
Answer the following questions on a separate sheet of paper. You can, and should, use the graph below for Question 1.
Use the illustration below to answer the following questions.
Position 1
Position 2
Position 3
Position 4
Position 5
1. For the pendulum pictured above, draw the bar graphs that show the relative amounts of kinetic energy (K.E.) and potential energy (P.E.) for pendulum positions 2 through 5. Position 1 is graphed for you. (Hint: think about the Ruff Ruffman Roller Coaster activity).
2. If the pendulum were to start its swing higher, would that affect its maximum gravitational potential energy? Explain.
3. Describe the process of energy conversion from potential energy to kinetic energy as water falls from the top to the bottom of Niagara Falls.
4. In terms of power and energy, explain why a 60-watt light bulb is brighter than a 25-watt light bulb.
The machine shown below drops the weight attached to the end of the pulley, called the pile driver, onto the support beam in the ground, called the pile. The force of the pile driver hitting the pile drives the pile farther into the ground.
Mass of pile driver = 5,000 kg
Velocity of pile driver = 4 m/s
Pile driver
Pile
Use the diagram above to answer the following questions in the spaces provided.
5. Calculate the kinetic energy of the pile driver in the figure above as it falls to hit the pile below it. Show your work.
6. How much gravitational potential energy does the pile driver have when it is lifted to a height of 15 m? Show your work.
7. Calculate the work done by a 47 N force pushing a pencil 0.26 m.
8. How much work is it to lift a 20 kg sack of potatoes vertically 6.5 m?
9. A 75 kg man pushes on a 500,000 kg wall for 250 s, but it does not move. How much work does he do on the wall?
10. What is the potential energy of a 2 kg potted plant that is on a 1 meter-high plant stand?
11. The potential energy of an apple is 6.00 joules. The apple is 3.00 meters high. What is the mass of the apple?
12. What is the kinetic energy of a 2,000 kilogram boat moving at 5 m/sec?
13. What is the mass of an object that creates 33,750 joules of energy by traveling at 30 m/s?
Essay
14. Two cyclists are riding their bikes up a steep hill. Jessica rides her bike straight up the hill. Adrian rides his bike up the hill in a zigzag path. Adrian and Jessica have identical masses. Once they reach the top of the hill, does Adrian have less gravitational potential energy than Jessica? Explain your answer.
15. How is the law of conservation of energy illustrated in the following situations: a person hitting a baseball with a bat, a person throwing a flying disk.
16. Calculate the work done by a 47 N force pushing a pencil 0.26 m.
17. How much work is it to lift a 20 kg sack of potatoes vertically 6.5 m?
18. A 75 kg man pushes on a 500,000 kg wall for 250 s, but it does not move. How much work does he do on the wall?
19. What is the potential energy of a 2 kg potted plant that is on a 1 meter-high plant stand?
20. The potential energy of an apple is 6.00 joules. The apple is 3.00 meters high. What is the mass of the apple?
21. What is the kinetic energy of a 2,000 kilogram boat moving at 5 m/sec?
22. What is the mass of an object that creates 33,750 joules of energy by traveling at 30 m/s?