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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Specialist Mathematics => Topic started by: k31453 on March 17, 2013, 09:37:57 pm

Title: Find work done??
Post by: k31453 on March 17, 2013, 09:37:57 pm: i got this question i m struggling the actual ans is given
Title: Re: Find work done??
Post by: Lasercookie on March 17, 2013, 09:50:56 pm: $\vec{W}=\vec{F}.\vec{x}=|F||x|cos\theta$

So the displacement vector is 22 feet along the ramp. You also know that the force vector is 80 pounds (yeaaaah pounds seems like an odd unit to use, but I guess just going along with it), along the rope.

We can also figure out the angle between the rope and the platform. 33 - 10 = 23 degrees. Draw it out if this isn't clear to you.

So $W = 80 \times 22 \times cos(23^\circ) = 1620$ (rounded off)

You're not going to get SI units out of this. Our force was in pounds, and our displacement was in feet, so our work is in units of foot-pounds