Recent content by Goofball Randy

I see, how clever! The mass center would be 1m away from the pole-thingy. So torque = 1 * 5 * 9.8 = 49. Thanks so much!

Oh! It wasn't, that was a straight up r x F calculation. See, I was confused by the part where the bar is attached "0.5m from the end". So I figured that the actual mass would not be 5kg, but rather 5 * (2.5/3), since that would be the fraction of the bar that I'm actually looking at.

I'm sorry, I don't understand. Are you saying I SHOULD be using inertia of a bar, I = 1/3 M r^2 ? Because right now I am literally just doing f = ma. And if I need to use inertia, should I use the torque = Inertia * angular acceleration equation?

Can you point out where? I thought I was calculating torque.

Do I need to calculate them individually? The correct answer here is 49, and I think my approach as a whole is wrong.

Homework Statement Homework Equations Torque = r X F The Attempt at a Solution r is 2.5m since that's the length of the red (minus 0.5), and F should be the weight, so ma? That gives something like (5 * 2.5/3) * 9.8 * 2.5, which doesn't give me an answer at all :(

Thanks guys! Seems really obvious now that I remember it.

Homework Statement Homework Equations The given elastic force equation The Attempt at a Solution I plugged in the numbers, with 0.2m for the change in s and 45 for a. Since I knew that work was equal to force * distance, I multiplied that result by another 0.2m. This got me 0.0144J, or...

Thank you for the help anyway :) I figured out the correct answer.

But the answer key says it's "D", or 2.5R. I don't understand why :(

I'm still confused :( How does finding the energy at the top help me to solve the problem? If KE is basically zero at the top of the loop, that would imply that it's all potential energy...are you saying that PE at the top of the loop is the same as the PE at the very start? Because that would...

Err, KE and PE are BOTH zero at the top of the loop? How does that make sense when considering the conservation of energy? (mgh + 0 = 0 + 0) Also, I'm not sure I get what you're saying...set PE equal to KE, isn't that what I did above?

Homework Statement Homework Equations Conservation of Energy (Potential + Kinetic = Potential + Kinetic) The Attempt at a Solution At the start of the ramp, potential energy is mgh (gravitational potential) and kinetic is 0, since it's not moving. At the bottom of the loop, potential...

Ahhhh never mind. I'm just bad at math. :D

Yeah, realized that from the other post. Edited my post above, but it still is wrong. I was so hoping it would be right too, since it made so much sense...