ok i know i hae asked a few physics questions but for some reason this subject is just way over my head but here is the problem half is in a picture but i think i can explain it ...
a uniform plank is 4.9m and weighs 218N... it rest horizontally on 2 supports.... (the left support is at the beginning of the plank) and there is 1.1 m of the plank hanging over the right support. to what distance, X can a person who weighs 444N walk on overhanging part of plank before it just begins to tip???
ok so i tried f net = o and torque net = 0 so first off is that even the right thing to do???
if it is i obviously got lost somewhere in the middle or didnt set it up right b/c when i solved it through i got x=4.73 whicch is obviously incorrect b/c there is only 1.1m hanging over so he can't walk further than that... please explain in detail i would like to see where it was that i messed up this problem so i can be prepared for hte other problems and for my exams
2007-03-08 11:48:21 · 4 answers · asked by imjustmewhatelseshouldibe 1 in Science & Mathematics ➔ Physics
First, the weight is not 218N, but rather 9.8 times smaller (22.25Kg)
When there is load on the plank from the the force exerted by the person (444N), you will have a level with one pivot point (the right support). You are correct to balance the torque.
The center of the mass for the plank is at position is at 1.35m left of the right support. The force due to mass of the person on the right must be positioned so that the torque is equal.
(1.35m)(218N) = 294.3Nm of torque
(x)(444N) = 294.3Nm
x = 294.3Nm / 444N = 0.663m
When the plank first starts to lift the person is 0.663M to the right of the right plank.
2007-03-08 12:16:30 · answer #1 · answered by Math Guy 4 · 0⤊ 0⤋
Yes, you're off to a good start. Sum of forces and sum of torques is zero. Remember, the plank itself has mass (calculate it's weight torque from the center).
So you can figure out how much weight is on the total of the two supports. When you're about to tip, all the weight is on the middle support. The center of mass of the person and the plank is right over it. That lets you solve for the person's position.
2007-03-08 11:53:01 · answer #2 · answered by Anonymous · 0⤊ 0⤋
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2016-12-18 18:22:35 · answer #3 · answered by ? 3 · 0⤊ 0⤋
Well i think your 4.73 is right it just means he could walk that far before it starts to tip. I can't be %100 sure with out the picture.
2007-03-08 12:05:06 · answer #4 · answered by scootergarrett 2 · 0⤊ 0⤋