Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

deeprony7

  • 4 years ago

A sphere of mass 50gm and radius 10cm rolls without slipping with a velocity of 5cm/s. Its total kinetic energy in ergs is?

  • This Question is Closed
  1. stan
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    For rolling w/o slipping, and choosing teh cm of the cm of teh sphere as the rotation point, \[K _{total}=K _{transl}+K _{rot}=1/2mv^{2}+1/2I \omega ^{2} = 1/2mv^{2}+1/2(2/5mr ^{2})(v/r)^{2}=7/10 mv^{2}\] You can also choose the point of contact as the rotation point and use teh parallel axis theorem to get the same answer

  2. deeprony7
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    how will i do that?

  3. stan
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Choose the point of contact as the rotation point... thus the point of rotation has been moved a distance r from the center of mass of the sphere. Parallel axis theorem says \[I _{\parallel} = I _{cm} + mr ^{2}\] where, again, r is the distance the point of rotation has been displaced from the center of mass (cm) of the sphere. Now, all energy is rotational: \[K _{total} = K _{rot} = 1/2 I _{\parallel} \omega ^{2} \] \[= 1/2 (2/5 mr ^{2} + mr ^{2})*(v/r)^{2}\] \[=1/2(7/5 mr ^{2})*(v ^{2}/r ^{2}) = 7/10 mv ^{2}\]

  4. deeprony7
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    interesting..=)

  5. dinainjune
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    8.75x10^(-5) Joule

  6. ac7qz
    • 4 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    You have a combination of linear and rotational KE. These guys are telling you true. P.S. Who uses ergs any more? I haven't heard the term since 1950s sci-fi.

  7. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy