Work, Energy, and Power unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
Kinetic energy
Why friction has no potential energy
Conservative vs non-conservative forces
Work
When mechanical energy is not conserved
Power
When to use energy instead of forces
Why carrying a box horizontally does no work
Conservative vs nonconservative force
Zero-work forces
Conservation of mechanical energy
Why the system boundary decides your equation
Short answer 1. Define or explain: Work done by a spring
3 ptsShort answer 2. Define or explain: Work from a force-distance graph
3 ptsShort answer 3. Define or explain: Choosing the reference height
3 ptsShort answer 4. Define or explain: Work done by friction
3 ptsFree response
9 ptsA 0.40 kg block is pressed against a spring of stiffness k = 500 N/m, compressing it 0.20 m on a horizontal surface. The spring is released. The block leaves the spring at point A, slides across a rough horizontal patch of length 1.5 m (μk = 0.25) to point B, then travels up a smooth curved ramp. Use g = 10 m/s² and ignore air resistance.
Calculate the energy stored in the compressed spring and the speed of the block at point A.
Calculate the energy dissipated by friction between A and B.
Calculate the maximum vertical height the block reaches on the ramp.
The experiment is repeated with a 0.80 kg block and the same spring compression. State whether the maximum height increases, decreases, or stays the same, and justify with equations.
Explain why an energy bar chart drawn for A, for B, and for the highest point must have the same total height in every column.