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Physics 11 Force and potential energy

  • Thread starter Iceclover
  • Start date
59
0
1. Homework Statement

A constant net force of 410N up is applied to a stone that weighs 32N. The upward force is applied through a distance of 2.0m andthe stone is then released. TO what height from the point of release will the stone rise?

2. Homework Equations

Ep=mgh

3. The Attempt at a Solution

Ep=mgh
410=32(h)
h=13m
 
482
1
I'm not sure where you're going with your solution.
Personally, I'd apply impulse again to get the stone's final velocity at the time of release, and then treat it as one-dimensional motion with constant acceleration.
 
59
0
i can't use impulse can I? i don't have a time?
 
482
1
Picky, picky....:blushing:

OK, how about the Work-Energy theorem to find the velocity at release?
 
59
0
Ek=1/2mv^2? and which force do i use
 
482
1

cristo

Staff Emeritus
Science Advisor
8,056
72
An easier way is to use the Work-Energy Theorem, as stated above. Calculate the work done by the force on the stone for the 2m that it is applied (recall, work done = force * distance). When the stone reaches its maximum height, all the energy is the potential energy, so you can equate the potential energy to the work done, and solve for h.
 
Last edited:
59
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Work done on object is equal to the change in its kinetic energy
 
482
1
OK, so can you apply it? (I know I can...)
 
59
0
what do i do once i've found velocity
 
482
1
Use a basic kinematics equation for motion with constant acceleration.
 
59
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the answer i got was 26m
 
482
1
Oddly enough, so do I.
 
59
0
ok good, thank you very much
 
59
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do you have time for another question?
 
482
1
Not really... but I'm in the middle of studying for my physics final, so this helps me, too. Look, If I don't answer, someone else will. (That's why this forum rocks!)
 
59
0
ok sounds good, i think im going to make a new topic though
 

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