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Mon 5 Dec, 2005 12:11 pm
ok i am in need of some serious help. i did this lab last week in physics on Forces in Equilibrium and i am stuck on the conclusion. the conclusion question is "what could be the reason for your two forces ( resultant force and acting force i guess cause thats what we've been working with) not to be exactly equal?" i don't know if i screwed up my calculations of acting force cause i just added the two forces together, because we were doing a pulley experiment where you had weights hanging on a string and the string was attatched to 2 newton metres. so yeah, very confused 11th grade physics student here.
Other forces in play
One reason could be that other forces are in play but you are not measuring them. For example, if you had to apply a larger force than expected to lift a weight on a pulley system, you are probably overcoming friction in the pulleys. Think of a rusted up pulley system. It takes a lot more force to use it than that required of a well oiled, clean system. Hope that helps.
Can you describe what the whole system looks like or give me a little diagram or something. I'm not sure how they are attached, maybe I can help then.
I think the explanation is more theoretical that rust causing friction because it is 11th grade. Usually they would say that the pully itself is frictionless.
Also remeber about solving pulling questions using Newton II: If a body is at rest then the Tension in the string or rope is = to the weight.
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