DP Physics (last assessment 2024)

Question 20N.2.HL.TZ0.b(ii)

b(ii).

[Maximum mark: 2]

20N.2.HL.TZ0.b(ii)

A nuclear power station uses U-235 as fuel. Assume that every fission reaction of U-235 gives rise to $180 MeV$ of energy.

The power station has a useful power output of $1.2 GW$ and an efficiency of $36 %$ . Determine the mass of U-235 that undergoes fission in one day.

[2]

Markscheme

energy produced in one day $= \frac{1.2 \times 10^{9} \times 24 \times 3600}{0.36} = 2.9 \times 10^{14} « J »$ ✓

mass $= \frac{2.9 \times 10^{14}}{7.4 \times 10^{13}} = 3.9 « kg »$ ✓

Examiners report

Most candidates had the right idea, but common problems included forgetting the efficiency or not converting to days.

Syllabus sections