Recent content by OME9A

I read that even with friction it is still closed because matter is not exchanged... Only heat/energy is exchanged. So then the conservation of momentum still applies, and the only reason for the difference is human error...right?

I understand that momentum is always conserved when there are no external forces, but I've read that if there are external forces, the conservation of momentum does not hold... So how can we create an equation that factors in the external forces since the loss of momentum is false? Is there...

so if it isn't closed, we have no way of calculating the correct change in momentum? Even if we know the external forces?

Right, but I thought that explained the loss in Kinetic Energy, not momentum...

Hmmm... but in all my experiments it is never conserved! So it's just "human error?" That sucks... I was hoping there was a cool explanation!

Conservation of momentum only applies when there are no external forces, so how would I add friction into the equation? For a sticky collision, p_{A1}+p_{B1}=p_{A2}+p_{B2} But I've seen that the momentum after is usually less than the momentum before (for a sticky, linear collision of 2...

I'm a beginner but maybe I can help put it in a simpler way-- Think of dropping a feather and a tennis ball at the same height. We learned that on the moon since there is no air resistance so they would reach the ground at the same time since the gravity and thus the acceleration is the same...

Thank you, it makes sense now!

Another force!? I can't believe how many forces there are in such a simple experiment... I hope we never get this far in physics; I have enough trouble dealing with just gravity, normal, and friction! Thanks, I will keep angular momentum in mind as well!

Okay, just so that I have this straight: On the way up the ramp, rolling resistance is acting in addition to friction so that both rolling resistance and friction add to the deceleration, but on the way down, rolling resistance and friction are pulling it upwards so it reduces the...

And another confusing find: As the difference between upwards and downwards accel. increased, the coefficient of friction increased. This is understandable because we used the formula that Coeff. of Friction= \frac{a_{up}-a_{down}}{-2gcos\theta} (g is positive 9.81) But the only...

We haven't learned this yet, but I did a quick google and found that it mainly exists for solids moving through liquids. Is it possible that a simple cart going up a ramp in the open (not underwater or anything...) could have a drag force equivalent to .05 m/s^2 deceleration? It seems like a lot!

Not just the accel. due to gravity, but the overall acceleration... We did an experiment around 5 times, and every time, the magnitude was greater on the way up (up to right before it has a velocity of 0 and starts coming down) than on the way down (up to right before it returns to its original...

Why is the magnitude of acceleration on a ramp greater on the way up than it is on the way down? I can't figure it out... I was thinking maybe it has something to do with the initial force applied to the cart on the way up the ramp? So that you know exactly what I mean: If I have a cart...