# Recent content by Winner

1. ### The central difference method! Help!

Hi guys. Ok I'm working on this problem, it's more theoretical than anything.:yuck: I'll try to explain as best I can. Lets say you have a runner going past the following points up till and past 30 m: Distance (x) of x1=0, x2=4, x3=9, x4=20, and x5=30m the times to these intervals are 0...
2. ### Confirm my logic on power

I see. So V=d/t, then use that as a final V in a=Vf-Vi/t, a=.4 m/s^2 on a non frictional surface. Sorry, I just didn't get the formulas Xiankai was using. I see! so if I had a coefficient of friction then I all I would do is go (40kg x 0.4 m/s^2) - u (mu) x F normal (m x g)...
3. ### Confirm my logic on power

So how does one do it in terms of the equation?
4. ### Confirm my logic on power

Ok, So, lets say I was to drag a 40kg load in a set distance of 10 meter. I record the time, it was 5 secs. Now I find power, P=work/t. We know work=force x distance. SO my question is, is force just mass of load x acceleration due to gravity? 9.81m/s^2. So P= ((40kg x 9.81) * 10...
5. ### Conceptual problem! Check my work :P

Wait, got an idea...What about if he rotates his leg in the opposite direction of his hand rotation? Ok..I'm going to go bang my head on the table now lol. This is nuts.
6. ### Conceptual problem! Check my work :P

See, now I'm really confused...Ok, it says describe two ways which we can stop his twisting while still in the air. So what Lightgrav suggested was 1)lift his right hand out of page and drop left one--wouldn't this cause him to start twisting the other way? 2)aren't his feet always beneath...
7. ### Conceptual problem! Check my work :P

So are you saying that if my guy spreads himself out, he'll eventually stop twisting because of his large Inertia which gives a small angular velocity as in H(ang momentum)=Iw? So can I say he can spread his hands out and spread his legs out as two different movements OR are they the same, ie...
8. ### Conceptual problem! Check my work :P

So, in my diagram I outlined the directions, did I do these right? I don't think he can "stop" his movement of falling down, but he can stop twisting. As I've noted, he might be able to life his right hand OR drop his left but are those considered different? By doing that he balances out his...
9. ### Conceptual problem! Check my work :P

Hey:smile: , The question: The athlete on the diagram (linked) is free in the air and has a total angular momentum as indiated by the red vector. 1)Indicate with a vector the direction of his twist based on his orientation and angular momentum, show how you got this. 2)Describe 2...

Title threads.... How come I can't edit my title threads anymore. I used to be able to do it. :confused:
11. ### Vertical Jump Test and physics! Check My Work

Anybody? it's due tomorrow, really need some advice. Thanks.
12. ### Vertical Jump Test and physics! Check My Work

The other case... Calculate the average force required to absorb the energy of your landing if you take 0.25 meters to stop. F=m(v2-v1)/t =68(0-3.05m/s)/t =68(3.05m/s)/0.082 =2529N? t=d/v t=0.25/3.05 t=0.082
13. ### Vertical Jump Test and physics! Check My Work

Ok, I think I got it? on the question where it asks: Calculate the average force required to absorb the energy of your landing if you take 0.25 meters to stop. Could it really be this simple? I know my energy for the jump is 323.5J. And to apply such a force to stop at 0.25m, I'd...
14. ### Finding MY center of mass!

You're lots of help! I wonder...I posted this https://www.physicsforums.com/showthread.php?t=96722 maybe you could give me some input. Much appreciated :).
15. ### Finding MY center of mass!

Ahhh, my sticky point was the distance from my backpack to my toes. Thought I had to calculate that :rofl: :rofl: . Ok, I think I got this. Thanks for the help.