haruspex's latest activity

It is called utility theory. Generally, the value one has for money is monotonically increasing but concave. The more you have, the...

Yes. because the hint says to take moments about P. Since the line of action of that force is through P, it has no moment about P...

I agree the collision example is ugly. First, it needs to be specified, symmetry wrt what? Let’s say it is the interchange of ##m_1##...

The Atwood example makes it clear what is intended. In that case, we should not expect the value of interest - the tension - to depend...

Just in case yet another way of putting it helps… - A force cannot balance a moment. The moment of a force can balance a moment. -...

You will need to be rather more specific for the question to be interesting. If you imagine changes to (i.e. deletions from) R in...

Have you quoted that correctly? When it contacts the spring, the spring is relaxed, so that is the equilibrium position. Does it...

That really does not help much by itself. Please take the trouble to post the working as well, typing the equations in, preferably...

You are entitled to know why. Is it possible to reply to the warning?

Yes, I do realise that. The purpose of my post was to challenge the statement I quoted in post #12 in a way that might convince the...

Centripetal acceleration is the component of acceleration that is normal to the velocity. If the plane is flying level, its lift is g...

I'll say it again more strongly. The only reliable way to handle an idealisation is as the limit of realistic versions. When there is...

"An infinite mass is placed on each side of a beam balance. By symmetry, they balance." In the real world, nothing is perfectly...

And the one knows what it says anyway, which helps.

I used to think that way, but then along came virtual particles. Those many philosophers who had been unhappy with forces magically...