A student tries to open a door by pushing on it in four different ways, P, Q, R and S.
The Table gives information about each push.
Table
| Push | Force in N\text{N}N | Distance from hinge in m\text{m}m | Direction of force |
|---|---|---|---|
| P | 20 | 0.75 | at right angles to the door |
| Q | 20 | 0.25 | at right angles to the door |
| R | 40 | 0.75 | along the door, towards the hinge |
| S | 10 | 0.75 | at right angles to the door |
Calculate the moment of push P about the hinge.
Explain which push, Q or S, produces the larger moment about the hinge.
Use calculations in your answer.
Push R is the largest force, but it does not open the door.
Explain why.
Calculate the force that the student would need to apply 0.25 m from the hinge, at right angles to the door, to produce the same moment as push P.