# Investigating the stability of a wooden block

Consider the above experimental design. At the end of the strip, at point $$p$$, a mass $$m$$ is attached, the stability of the wooden block above is determined by the angle $$θ$$ at which the block topples over. It seems that as the angle $$θ$$, approaches $$0$$ the block becomes easier to topple over. However, I am struggling to come up with a suitable reason for why.

At all values of the angle $$θ$$, the distance of the mass $$m$$ from the centre of the mass remains constant. Hence, the only thing that changes is the area of the strip over the top of the block. So then, is a suitable explanation, that the force downwards by the mass $$m$$ is distributed over a larger area, making the turning effect of the force less?

Another explanation I have come up with, is that the edge of the block that the strip is over, acts as the pivot for the mass $$m$$. As the strip angle increases, the distance between $$p$$ and the pivot actually decreases, therefore making the turning effect of the force less. Is this suitable?

I am looking for a sound physics explanation for the phenomena above. My attempts at explanations do not seem correct.

• Stability and toppling Commented May 3 at 9:33
• "edge of the block that the strip is over" Yes, that is the reason. Commented May 3 at 11:48
• This seems to be a conceptual question with a conceptual answer. Voting to re-open. Commented May 3 at 13:02

Another explanation I have come up with, is that the edge of the block that the strip is over, acts as the pivot for the mass $$m$$
This is the correct explanation. If the block (or the bench that it sits on) is tilted, it will topple once a vertical line through the centre of gravity of the block/mass system moves outside of the base of the block. Decreasing the angle $$\theta$$ moves the mass at $$P$$ further away from the block, thus moving the centre of gravity of the block/mass system towards the right hand edge of the block, making the block easier to topple. If $$m$$ is sufficiently large compared to the mass of the block then there may even be an angle $$\theta > 0$$ at which the centre of gravity moves outside of the block and the block topples without being tilted.