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Date November 2020 Marks available 2 Reference code 20N.3.SL.TZ0.7
Level Standard level Paper Paper 3 Time zone 0 - no time zone
Command term Explain Question number 7 Adapted from N/A

Question

The first diagram shows a person standing on a turntable which can rotate freely. The person is stationary and holding a bicycle wheel. The wheel rotates anticlockwise when seen from above.

© International Baccalaureate Organization 2020.

The wheel is flipped, as shown in the second diagram, so that it rotates clockwise when seen from above.

© International Baccalaureate Organization 2020.

Explain the direction in which the person-turntable system starts to rotate.

[3]
a.

Explain the changes to the rotational kinetic energy in the person-turntable system.

[2]
b.

Markscheme

«person rotates» anticlockwise

the person gains angular momentum «in the opposite direction to the new wheel motion»

so that the total angular momentum is conserved

 

OWTTE

Award [1 max] for a bald statement of conservation of angular momentum

a.

the rotational kinetic energy has increased

energy is provided by the person doing work «flipping the wheel»

 

OWTTE

b.

Examiners report

[N/A]
a.
[N/A]
b.

Syllabus sections

Option B: Engineering physics » Option B: Engineering physics (Core topics) » B.1 – Rigid bodies and rotational dynamics
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Option B: Engineering physics » Option B: Engineering physics (Core topics)
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