Physics 1-7-09 Collisions Problems Review
PHYSICS: You did a great job on the problems in class today. Are you understanding better how to set them up? Some of the ones tonight are a little tough, but you can do it! Don’t you just love these pics of unique “collisions”?
January 7th, 2009 at 11:02 PM
I’m a little confused about the formula to find the decrease or change in kinetic energy for a collision-like on number 31 part b on pg. 225.
On the video, we first used KE=(1/2 m vf^2) – (1/2 m vi^2)
Then, Ms. Skinner used two formulas:
KEti=KE1i+KE2i and KEtf=KE1f+KE2f.
So do we use the first formula at all?
And I think we use KE=1/2 m v^2 for every KE in the second set of formulas, right?
I’M SO CONFUSED!
shelby :]
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January 7th, 2009 at 11:53 PM
Gah! These problems are owning me… x_X
Could anyone help me out with the problems finding a mass and velocity with only a given KE and momentum?
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January 8th, 2009 at 9:08 PM
Does anyone know how high the school balcony is?
I think i remember doing a lab when we had to measure it but I dont remember lol.
so anyways, if someone with awesome memory would like to tell me that’d be amazing. =)
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January 8th, 2009 at 9:26 PM
Shelby: Were you able to figure out the KE dilemma in class today? If you’re looking for the change in KE of one thing, you do its KE final minus the KE initial. If you need a total change in KE, you find the final KE of everything in your system (each things final KE added together) and then subtract the total initial KE of everything in the system (everything all added together.) Hope that helps!
Alex: Hope the problem review helped in class today. You might watch the problem review vodcasts again. Let me know if we need to have another help session in the morming before the test!
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January 9th, 2009 at 12:35 AM
Alex: Solve the formulas KE = (1/2)mv² and p = mv for m. Since you’ll have two equivalents for m after that, set those two formulas equal to each other and solve for v. Once you have the velocity, it is easy to find the mass.
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January 9th, 2009 at 6:32 PM
Lauren: I think I remember the balcony being something like 5.2 meters, but that might be a little off. I know it was a little over 5 meters because I remember having to measure it in that lab. I hope that helps!
Are you testing it from your balcony at home?
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