Question

Question #5c358

Answer 1

The weight of S is 16N

Explanation:

You need to consider moments about the fulcrum (the knife edge). Looking at the weights on the right hand side (clockwise moments).
The moments are:

• `10N times 0.2m` -the weight acting at the centre of the rod which is 20cm from the fulcrum; and
• `8N times 0.35m` -the 8N weight that is 35cm from the fulcrum.

So total = `2Nm + 2.8Nm=4.8Nm`

For the system to be in equilibrium, this must equal the anticlockwise moments due to the unknown solid =`S times 0.3m`

Hence

`0.3S=4.8`
so `S=4.8//0.3=16N`