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  1. R

    Question about momentum ?

    Rolling friction ? Never heard of ?
  2. R

    Question about momentum ?

    Oh yeah, my bad... velocity times mass... I always mix up with impulse lol :S, but yeah I guess friction is part of the experiment ? However... when you take the bucket of sand off, the friction stays the same ?
  3. R

    Question about momentum ?

    1. Homework Statement Ok so my teacher used this example in class, he had this flat wheeled cart rolling on the floor. The object was to release a bucket of sand on top of the flat cart to see if the cart would slow down or accelerate. Easily, all of us the students predicted that the cart...
  4. R

    Speed problem

    Thanks a lot guys!
  5. R

    Speed problem

    I have an awnser sheet and it says 2m/s... I'm supposed to find what force pushed the cart above the second hill which I assume is kinetic energy but I have no mass wich I don't understand...
  6. R

    Speed problem

    1. Homework Statement I have to find the speed needed to push a cart on top of a hill and I only have the height as a number. 2. Homework Equations A boy places his matchbox car at the top of the track he has set up with his brother. If the track starts atop the 55 cm toy box, descends...
  7. R

    Need help with homework

    1) Slower, because the water makes it hard to accelerate which I don't know how to explain 2) The car tire that is properly inflated because... AIR!
  8. R

    Car & Gasoline

    To move, or for transportation ?
  9. R

    Need help with homework

    1)Well depending on steel's density, it would either find itself at the botom of water or float to the top without even following the pattern 2)Friction ?
  10. R

    Car & Gasoline

    Heat.. nuclear.. electric ??
  11. R

    Need help with homework

    1) No, that's not what I'm talking about. What else is different about the moon, other than the 1/6 gravity? Its lighter 2) No, assume that they both have enough friction on the ramp so that they do not slip. What is the main difference between steel and rubber (other than mass density)...
  12. R

    Car & Gasoline

    1. Homework Statement How does the amount of work done on an automobile by its engine relate to the energy content of the gasoline ? 2. Homework Equations How does the amount of work done on an automobile by its engine relate to the energy content of the gasoline ? 3. The Attempt...
  13. R

    Need help with homework

    Wait, sound dosen't produce by itself... it must have something to make it happend... wouldn't that something be kinetic energy ? WHICH would explain why there is missing energy ! IS that it!!?
  14. R

    Need help with homework

    I really don't know, we haven't worked with sound yet... I'd say steel surface is different than rubber... :S
  15. R

    Need help with homework

    OK, :confused: Don't give up on me, here's my try. 1) I think on the moon, if there was no force applied on the ball, it would move slower because the gravity is lower than earth ? 2) A steel ball has greater acceleration than the rubber because they have different friction. 3)...
  16. R

    Need help with homework

    Different friction between 2 objets maybe ? IDK lol :S! :cry:
  17. R

    Need help with homework

    Well in the moon wouldn't the speed be constant no matter what ? And a steel ball... dosen't it depend on its mass... I mean shouldn't it have more PE to convert to KE then the rubber ball??? AM I right or does this make total nonsense lol ?
  18. R

    Need help with homework

    Okay here is my question.:shy: If Total Energy should be constant, because the loss in Potention energy should equal a gain in Kinetic Energy, where does the missing total energy go to ? Here is my data; TOTAL ENERGY: MISSING ENERGY: .1254...
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