Oscillations 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.
Small-angle approximation
Simple pendulum period
Limits of the pendulum formula
Period of a spring on a different planet
Damping
A spring keeps the same period on the Moon
Velocity leads displacement by a quarter cycle
Energy trades twice per cycle
Period of a simple pendulum
Where acceleration is maximum
Mass-spring period
Velocity and acceleration in SHM
Short answer 1. Define or explain: What is absent from the period formulas
3 ptsShort answer 2. Define or explain: Amplitude independence
3 ptsShort answer 3. Define or explain: Simple harmonic motion
3 ptsShort answer 4. Define or explain: Phase
3 ptsFree response
9 ptsStudents investigate a vertical spring. They hang a known mass m from it, pull the mass down a small distance, release it, and time 20 complete oscillations with a stopwatch. They repeat for several masses and plot T² (vertical axis) against m (horizontal axis). The graph is a straight line through the origin with slope 0.80 s²/kg. (a) Starting from T = 2π√(m/k), show why a graph of T² versus m should be linear and state what the slope represents. (b) Calculate the spring constant k from the slope. (c) Explain why the students timed 20 oscillations instead of one, in terms of experimental uncertainty. (d) A student suggests the period would be shorter if the experiment were repeated on the Moon, where g is about one-sixth of its Earth value. Evaluate this suggestion and contrast it with a simple pendulum. (e) Predict what happens to the measured period if the students double the (still small) amplitude, and justify your answer.