Question 19M.2.HL.TZ1.a.iii
| Date | May 2019 | Marks available | [Maximum mark: 2] | Reference code | 19M.2.HL.TZ1.a.iii |
| Level | HL | Paper | 2 | Time zone | TZ1 |
| Command term | Show that | Question number | a.iii | Adapted from | N/A |
A small metal pendulum bob is suspended at rest from a fixed point with a length of thread of negligible mass. Air resistance is negligible.
The pendulum begins to oscillate. Assume that the motion of the system is simple harmonic, and in one vertical plane.
The graph shows the variation of kinetic energy of the pendulum bob with time.
The mass of the pendulum bob is 75 g. Show that the maximum speed of the bob is about 0.7 m s–1.
[2]
mv2 = 20 × 10−3 seen OR × 7.5 × 10-2 × v2 = 20 × 10-3 ✔
0.73 «m s−1» ✔
Must see at least 2 s.f. for MP2.
This question was well answered. This is a “show that” question so candidates needed to clearly show the correct calculation and write an answer with at least one significant digit more than the given answer. Many candidates failed to appreciate that the energy was given in mJ and the mass was in grams, and that these values needed to be converted before substitution.
