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.
Reading kinetic energy from a potential curve
Net work and the work–energy theorem
Power as the rate of doing work
When to use energy rather than forces
Work by gravity is path independent
Efficiency
Instantaneous power as force dotted with velocity
Nonconservative work
Stability from a potential curve
Gravitational potential energy near the surface
Deriving force from U(x)
Escape velocity
Short answer 1. Define or explain: Thermal energy from friction
3 ptsShort answer 2. Define or explain: Units of energy and power
3 ptsShort answer 3. Define or explain: Energy in a spring-mass system
3 ptsShort answer 4. Define or explain: Escape speed is mass independent
3 ptsFree response
6 ptsA block of mass m is released from rest at the top of a curved, frictionless ramp of height h. At the bottom, it enters a rough horizontal surface with a position-dependent coefficient of kinetic friction μ_k(x) = cx, where c is a positive constant and x is the distance along the rough surface.
Derive an expression for the speed of the block at the bottom of the ramp.
Set up, but do not evaluate, an integral expression to find the total distance D the block travels on the rough surface before coming to rest.
Determine D in terms of m, g, h, and c.