Recent content by Bonulo

Yup, that's more like it! Or, it's exactly it, rather. We did have some notion about this actually, though not a clarified one.

What I wrote to ii) was the result as stated in the solutions we got. There, the speed decreases, as does the momentum and kinetic energy.

We have a physics exam tomorrow, and have been presented with a previous exam for practice. One of the assignments have puzzled us quite a bit. Here goes: Rain in a train wagon Consider a train wagon whose upper part is a lidless box. The train wagon moves without friction. There is water in...

When a refrigerator has been turned on for some time, steady state refrigeration occurs. This is the normal refrigerator operative state. But what exactly happens? These things are really hard to do research on, since Internet searches, regardless of search query detailing, result in a lot...

I'm working on a project about cooling and heating, and have a couple of questions needing answers/clarification: Entropy in refrigeration: The pV-diagram for the phase change refrigerator is that of the reversed Otto cycle. This cycle contains two adiabatic and two isochoric processes...

Guesses at answers Thanks for the quick reply! I'm prone to thinking that the answer in 1) is a spiralling orbit, which would make 2) the hard-to-determine-one (since the type of orbit would be hard to determine). However, if the orbit isn't closed, it might be 3) that's hard to...

I've been presented with the following problem: Problem: As a thought experiment it's presumed that the attracting force of gravitation instead of being inversely proportional to r^2, is inversely proportional to r^3. How does this theory change Kepler's 3 laws? (For one of the laws it...

I get the following expression for the time: t = (v_0 - \omega_0 r)/(-3/2 \mu_k g) Where the 0 suffix indicates the velocities immediately following the shot, and the \mu_k is the coefficient of kinetic friction (exerted during the slide). Does it seam reasonable?

Problems I'm having problems with b) and c), and the assignment's due tomorrow! In b) - there is constant acceleration (also angular), but - the rotational velocity changes direction, so I'll have to use two periods of time t , right? One for the time up to the point where the rotational...

Good, thanks Doc Al, Meir Achuz and DaMastaofFisix!

Yup ;) I'd merely choked on one of the equations. And regarding the explanation using conservation of energy; I conclude that the largest U2 (for the greatest height) equals K1 - on the rough surface. Since there is a K2 (only the rotational kinetic energy) - on the smooth surface: U2 =...

I tried again, and got a = - 5/7 g sin(\theta) which is smaller than in the smooth situation.

A possible solution (with N2) Yeah, I forgot that. Then: I calculate the two accelerations (linear and angular), put them in a = \alpha R , determine f (the friction) thus solving for the linear acceleration: SMOOTH SURFACE (no friction): a = - g sin(\theta) . ROUGH SURFACE...

Well, there is rotational kinetic energy in both cases - since the ball's rotating before hitting the incline. But it isn't converted into potential energy in the case of the smooth incline. I think. Using Newton's laws I see that the rough surface has a positive linear acceleration that's...

Yeah, I found out about that shortly after the posting. So: a) Rotational kinetic energy can only be utilized for forward linear motion if the surface is not smooth. b) The friction exerts upward force, but it also exerts a torque. Does the torque affect the linear, tangential...