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: Moving object on a moving slope

  1. Dec 16, 2014 #1
    1. The problem statement, all variables and given/known data

    Our teacher asked us today,to figure out,what the effect would be if the generic slope we use in most exercises would move too.That means,a mass m is sliding downwards to the right from a slope that is moving to the left.
    So,I don't want you guys to solve my home work for me,but I hoped to find here some keywords for things I have to look up.I honestly don't know what to google to solve this problem.
    Thank you!
    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Dec 16, 2014 #2
    what kind of effect would you want? observations? or identify all forces? make it clear.
  4. Dec 16, 2014 #3
    hello cheah10!
    She didn't specify,would you kindly provide me with keywords for both?thanks!
  5. Dec 16, 2014 #4
    If you are asking for the affecting forces ,,
    They will be as the following :
    the components of the gravitational force acting on the mass + the normal force on the mass from the moving slope + the frictional force .
    The resultant acceleration of the net forces is measured relatively to the movement of the moving slope if it goes with an acceleration , if the moving slope has a constant speed , "no acceleration" the resultant acceleration might be measured like the static slope.

    I think that might be a reasonable intuition but I'm not very sure.
  6. Dec 21, 2014 #5
    ok, I'll guide you from here. 1st, tell me, what are all the forces you can identify? Maybe it's better if you draw a free body diagram for both the slope and the mass, and upload it here.
  7. Dec 21, 2014 #6


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    It depends why the slope is moving. I would guess that the idea is the slope consists of a wedge which can slide on surface of a different angle (usually horizontal). It might help to start with an extreme case. What if the wedge is much lighter than the mass on it and there's very little friction?
  8. Dec 22, 2014 #7
    I understood that the slope is moving in a direction against to the motion of the object moving on it. not in a vertical motion , Where in the question did he specify that ?

  9. Dec 22, 2014 #8


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    I didn't suggest the wedge was moving purely vertically. As I wrote, it's probably to be considered as moving horizontally, but it could be more general.
    As for 'against', it depends what you mean by that. In most such problems, the wedge is moving only because of the normal force from the mass. So, yes, it moves in the opposite direction to the mass's horizontal motion, but I wouldn't describe that as 'against' it.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted