haruspex's latest activity

That gives the right moments equation, but it is not right as a force diagram. The weight W, applied where it is, is not equivalent to...

@gleem is taking moments about P, not O. I see no conflict.

How come you have relocated W to act at point O? The horizontal distance from P to the hanging mass is what matters.

Is it possible to move between sections? If so, maybe some not intending to use phones moved to where phone usage was low.

Because I could not be sure which you wanted and I felt it would be an easy mistake to make. But you seem to know what you are doing.

Yes, just be clear about which reference frame you want.

That is called coalescence. It is the case which maximises the lost KE and corresponds to coefficient of restitution = 0. Yes. In...

True, I was being lazy, which could mislead a student .I should have specified mechanical energy. Ah, no, that doesn’t do it because...

Yes, use momentum, but that is only one equation and you need two. Are you familiar with coefficient of restitution? That is a property...

Because you are specifying an impossible combination of conditions. In an actual one dimensional collision, there are two unknowns, the...

Your first calculation doesn’t assume "all the energy is transferred to the target". It assumes the target gets all the energy the...

Here's the animation from the wiki page: The effect is vastly downgraded, as the rope's expansion is on the same order of magnitude as...

The ant is always advancing to a new bit of rope, so it covers an increasing fraction of the rope. As that fraction increases, the...

Edit: only just saw @Ibix' solution. Seems to be even a very similar choice of variable names. The rope starts at length L and grows...

This is a common misconception. When you draw a force in an FBD, the direction shown only says which direction you are taking as...