Recent content by matthewpowers

Well, the question des say it's elastic, and that's why you can use both conservation of momentum and conservation of energy like you do to solve for the two final velocities, and then use v2f as the initial velocity for it compressing the spring. Right procedure, looks like you just messed...

Everything looked good up until this very last equation. How did you get 9=v2f? Did you add the equation before it to the conservation of momentum equation earlier so that the v1f term went to zero? If so, you just did your addition wrong...You should have: 1.6 = .2*v1f + .6*v2f -> from...

One thing I want to point out before you leave this problem that might make your life a little easier. You knew that the equation was v=Awcos(wt), and you knew that the maximum value the cosine function can be is 1 and the minimum (absolute value) is 0. Knowing this, you can just replace the...

Oh, and your aplitude should be .0085, not .00425, so you would be getting half the correct answer for the max...

Well, I think one of them is right...I'm pretty darn sure the min is zero (which is what 2.18x10^-17 is). What are the correct answers?

The pi/2 and 0,2pi are the values of wt that make the cosine function 0 and 1, respectively. By doing what you did, you are saying v = Aw*(wt), as opposed to v=Awcos(wt).

You should be able to use zero, just as well as 2pi...

And your calculator is in radian mode right. :)

right, wt=0 -> velocity is max, wt=pi/2 -> velocity is minimum. What are those maximum and minimum velocities?

Not quite. The velocity will be largest when [cos(wt)] is at it's largest (the whole cosine function, not what's inside the cosine function, since what's inside the function can get very large if time gets very large. But no mater how big (wt) gets, the cosine function never gets larger than a...

Yeah, if you write the two equation symbolically, and keep your masses straight, it should become clear.

The potential energy of a point charge is just U=qV, where q is the charge on the point charge, and V is the electric potential (as opposed to potential energy, which is U!) that charge is sitting in. And, to find the electric potential, V,(again, not energy) generated by a point charge, it is...

Before I go any further, I want to make sure that we are thinking of the situation in the same way. When I first read this problem I was confused because I thought that what happened was block one hit block 2, and both block one and block two together compressed the spring, and then block one...

Although, I do believe you have to find m2 by some other means (which the original poster did just fine I think) before you can use conservation of energy and momentum to solve for the velocity...otherwise you have 3 unknowns and 2 equations

It is with this last statement to which I was initially referring...you talked here about using a phi of zero when t=0 to make x=0. This is what prompted me to make the post.. However, you seemed to realize that phi=0 was not right for the displacement here. But you do still want to...