1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Rotational force

  1. Apr 17, 2008 #1
    1. The problem statement, all variables and given/known data

    Beverage Engineering. The pull tab was a major advance in the engineering design of beverage containers. The tab pivots on a central bolt in the can's top. When you pull upward on one end of the tab, the other end presses downward on a portion of the can's top that has been scored. If you pull upward with a 10 N force, approximately what is the magnitude of the force applied to the scored section?

    2. Relevant equations

    3. The attempt at a solution

    Now at first I thought that the force down just had to be the opposite of the force up, which would be -10 N. But I didn't think this problem could be that easy...

    So since the tab pivots on a central bolt the torque=inertia * angular acceleration (newtons second law)
    Now we don't know the mass of the can, so we cannot find inertia or acceleration. I think that since there is nowhere to go, it must be -10 N? I just can't see the problem being that simple

    Thanks! Any push in the right direction would be great.
  2. jcsd
  3. Apr 17, 2008 #2
    I dont think it will be -10N because you're neglecting the force due to the central bolt. You're going to have to take that into account and then probably just use newtons second law and some torque relations.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook