Recent content by PeteSeeger

Ah, ok, now I understand. Thanks everyone.

Homework Statement Sand runs from a hopper at constant rate dm/dt onto a horizontal conveyor belt driven at constant speed V by a motor. (a) Find the power needed to drive the belt. (b) Compare the answer to (a) with the rate of change of kinetic energy of the sand. Can you account for the...

P=Fv, and F=(dm/dt)V, so P=(dm/dt)V2

Thanks for the reply. I thought kinetic energy was a defined to by (1/2)mv2, so that in this case work wouldn't be simply the change in kinetic energy, but is it instead defined to be the integral of force (so that work will always be the difference of kinetic energy)? That would resolve things.

I have thought about this more and I will give a theory of mine. When the snow lands in the cart, the second the cart contacts the snow it exerts a force to speed it up. At the same time, the snow exerts a force back trying to slow down the cart. So, the cart must overcome the equal and opposite...

I am thinking about something that is getting me quite confused. To illustrate what is confusing me let's have a cart moving in the horizontal direction on a track without friction, and a motor which adjusts to keep the kart at a constant speed V in the positive direction. Now, it's snowing so...