7 (a) Which of these is a vector? A distance B force C mass D work done Calculate the value of W, the weight of child Q - Edexcel - GCSE Physics - Question 7 - 2023 - Paper 2

To find the weight W of child Q, we can use the principle of moments. According to the problem:

$$ext{moment of } W = ext{moment of the weight of child P}$$

The moment can be calculated using the formula:

$$ext{moment} = ext{force} imes ext{distance}$$

Substituting for the given values and distances will allow us to solve for W. Ensure the answer is rounded to 2 significant figures.

A crowbar acts as a lever, which allows a person to lift a heavy weight more easily by using the principle of moments.

Lever Mechanics

1. Lever Arm: By increasing the distance from the pivot (fulcrum) to the point where the force is applied, the required input force to lift the heavy weight decreases. This illustrates the concept that force x distance remains constant across the lever.

2. Applied Force: The force applied at the end of the crowbar is significantly smaller than the load that needs to be lifted. For example, if the distance from the load to the pivot is much smaller than the distance from the applied force to the pivot, the crowbar allows a larger mechanical advantage.

3. Direction of Force: By pulling down on the end of the crowbar, the other end pushes upward against the load, enabling the lifting of heavy objects with less effort.

In summary, the mechanical advantage offered by the crowbar allows a user to apply a smaller force to lift heavier loads effectively.