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Two children, A and B, are sitting on a see-saw, as shown in Figure 14 - AQA - GCSE Physics - Question 8 - 2018 - Paper 1
Question 8
Two children, A and B, are sitting on a see-saw, as shown in Figure 14. The see-saw is balanced. Figure 14 Use the following equation to calculate the moment of ch... show full transcript
Worked Solution & Example Answer:Two children, A and B, are sitting on a see-saw, as shown in Figure 14 - AQA - GCSE Physics - Question 8 - 2018 - Paper 1
Step 1
Use the following equation to calculate the moment of child B about the pivot of the see-saw.
Answer
To calculate the moment of child B about the pivot, we use the formula:
Here, the force exerted by child B is 280 N and the distance from the pivot is 0.9 m (which is 90 cm). So the calculation will be:
Thus, the moment of child B about the pivot is 252 Nm.
Step 2
Use the idea of moments to explain what happens when child B moves closer to the pivot.
Answer
When child B moves closer to the pivot, the clockwise moment exerted by child B decreases. This change makes the clockwise moment less than the anticlockwise moment exerted by child A.
As a result, the balance of the see-saw is disrupted, causing child A to move downwards and child B to move upwards. This demonstrates the law of moments where the balance depends on the relative distances and weights of the children.