Question 19M.2.SL.TZ1.5c
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.2.SL.TZ1.5c |
| Level | SL | Paper | 2 | Time zone | TZ1 |
| Command term | Describe | Question number | c | Adapted from | N/A |
A small metal pendulum bob of mass 75 g is suspended at rest from a fixed point with a length of thread of negligible mass. Air resistance is negligible. The bob is then displaced to the left.
At time t = 0 the bob is moving horizontally to the right at 0.8 m s–1. It collides with a small stationary object also of mass 75 g. Both objects then move together with motion that is simple harmonic.
Describe the changes in gravitational potential energy of the oscillating system from t = 0 as it oscillates through one cycle of its motion.
[1]
maximum GPE at extremes, minimum in centre ✔
This straightforward question had surprisingly poorly answers. Candidate answers tended to be overly vague, such as “as the bob went higher the GPE increased and as it fell the GPE decreased.” Candidates needed to specify when GPE would be at maximum and minimum values. Some candidates mistakenly assumed that at t=0 the pendulum bob was at maximum height despite being told otherwise in the question stem.
