Posted by Hannah on Sunday, January 20, 2008 at 10:24pm.
A 10-kilogram body is constrained to move along the x-axis. The potential energy U of the body in joules is given as a function of its position x in meters by:
U(x) = 6x^2 - 4x + 3
The force on the particle at x=3 meters is?
Here was my thinking.... U=-W. So, W(x) = -6x^2 + 4x - 3. W also = Fxcos(theta). So I plugged in x=3 to all x's to get Fcos(theta) = -3, so the force would be 3N to the left. Why is this incorrect????? Am I thinking way off track???
physics - bill j., Sunday, January 20, 2008 at 10:37pm
Yeah you're a little off track but not by far someone a little more knowledgeable would be able to give the correct formula and answer
physics - Hannah, Sunday, January 20, 2008 at 10:41pm
I just realized I totally forgot to include the mass. Can anyone help???
physics - bobpursley, Sunday, January 20, 2008 at 10:53pm
INT Fdx= U
F= dU/dx= you do it.
physics - bill j., Sunday, January 20, 2008 at 10:55pm
YEAH that's it, thanks bobpursley
physics - Hannah, Sunday, January 20, 2008 at 11:04pm
I thought U was the negative integral of Fdxcos(theta)? But I guess I was wrong...
physics - Hannah, Sunday, January 20, 2008 at 11:06pm
OK now it makes sense. The cos(theta) doesn't come in until the end, right? I got an F and then it's either neg or pos according to the angle. Thanks Bob (and Bill)
physics - bobpursley, Sunday, January 20, 2008 at 11:09pm
Hannah. Isnt costheta=1 here?
The negative sign takes care of direction of F (it is a vector). Think about that.
Answer This Question
More Related Questions
- Physics - A body of mass m= 1 kg is moving along the x-axis. Its potential ...
- Physics Classical Mechanics - A body of mass m= 1 kg is moving along the x-axis...
- Physics Please help !! - A single conservative force = (6.0x - 12) N where x is ...
- Physics - An 80 kg hiker climbs a 1000 m high hill at a constant speed. If the ...
- College Physics - The only force acting on a 3.9 kg body as it moves along the ...
- Physics - A body moves in rectilinear motion along the x-axis with an ...
- Physics - A 2.9 kg body is at rest on a frictionless horizontal air track when a...
- Physics - The position of a body moving along x-axis at Time t is given by x=(t^...
- Physics - The only force acting on a 4.7 kg body as it moves along the positive ...
- physics - The only force acting on a 3.0 kg body as it moves along the positive ...