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Homework Help: Spring on incline

  1. Oct 3, 2004 #1
    A 2.2 kg block is placed against a spring on a frictionless 25o incline (Fig. 8-37). The spring, whose spring constant is 27.6 N/cm , is compressed 27.6 cm and then released.

    (a) What is the elastic potential energy of the compressed spring?

    (b) What is the change in the gravitational potential energy of the block Earth system as the block moves from the release point to its highest point on the incline?

    (c) How far along the incline is the highest point from the release point?

    For part a) i got 105.122 J and that was right. I'm having trouble with parts b) and c)

    I don't understand how to find the height of the incline. i know u=mgh
  2. jcsd
  3. Oct 3, 2004 #2
    You're not asket to find the height of the incline. You're asked to find the highest point the block will reach ON the incline.
  4. Oct 3, 2004 #3
    that is what I meant in my question, how to find the heighest point on the incline.
  5. Oct 4, 2004 #4
    Great since you have no friction, you can apply the principle of energy conservation right away.

    You can do (c) two ways: either by finding the height the block rises above the horizontal or by computing the length along the incline directly. What is your specific problem with (c)?

    I suggest drawing a freebody diagram showing clearly all the forces which act on the body during its motion along the incline.

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