DP Physics (last assessment 2024)
Question 18M.3.SL.TZ1.6c
| Date | May 2018 | Marks available | [Maximum mark: 2] | Reference code | 18M.3.SL.TZ1.6c |
| Level | SL | Paper | 3 | Time zone | TZ1 |
| Command term | Calculate | Question number | c | Adapted from | N/A |
c.
[Maximum mark: 2]
18M.3.SL.TZ1.6c
A constant force of 50.0 N is applied tangentially to the outer edge of a merry-go-round. The following diagram shows the view from above.
The merry-go-round has a moment of inertia of 450 kg m2 about a vertical axis. The merry-go-round has a diameter of 4.00 m.
A child of mass 30.0 kg is now placed onto the edge of the merry-go-round. No external torque acts on the system.
(c)
Calculate the new angular speed of the rotating system.
[2]
Markscheme
«I = 450 + mr2»
I «= 450 + 30 × 22» = 570 «kgm2»
«L = 570 × ω = 747»
ω = 1.3 «rads–1»
Watch for ECF from (a) and (b).
Accept BCA, values in the range: 1.25 to 1.35.
[2 marks]
