O-LevelPhysicsForces5054/21 · May/June 2017 · Q24 Marks
Fig. 2.1 shows a student sitting on a chair. Fig. 2.2 shows the same student with his chair tilted backwards slightly. [Figure 2.1, Figure 2.2]
- (a)State and explain how the pressure of the chair on the floor differs in the two positions.[2]
- (b)The chair and student fall over if the chair is tilted backwards more than in Fig. 2.2. Explain why.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (May/June 2017). The mark or mark type is shown in brackets.
- [1] greater pressure in Fig. 2.2 and smaller area (in contact) in Fig. 2.2 or more force through the back legs
- [1] pressure is inversely proportional to area or pressure is force / area
- [1] centre of mass (on or) outside base / chair / leg
- [1] weight acts on left of / outside chair leg
- [1] (anticlockwise) moment (created)
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