Huh
Edit: I also used to post study aids on my blog.
EX:
Guide to 009:
An 71.9 N box of clothes is pulled 14.1 m up a 32.7 ramp by a force of 120 N that points along the ramp.
The acceleration of gravity is 9.81 m/s^2.
If the coefficient of kinetic friction between the box and ramp is .23, calculate the change in the box's kinetic energy. Answer in units of J.
First, solve for net force, or Fapplied-Ffriction-Fgravity. Fa is given (120 N), Ff is found through mK=Ff/Fn. Fnormal is weight times cosine theta. In this case, .23=Ff/71.9cos32.7. Fg is found by multiplying weight and sine of theta, or 71.9sin32.7. Fa-Ff-Fg=Fnet, in my problem's case 67.2 (don't round for problem, I'm just not bothering to type it out).
Now, solve for acceleration. Fnet=massXacceleration; thus you must solve for mass. Divide weight by 9.81 (71.9/9.81). When the number from the first step is divided by the mass, you can plug everything into the kinematic equation Vf^2=2ax.
This problem's acceleration is 9.17, so Vf^2=2(9.71)(14.1). Or, final velocity equals 16 point something.
Once you have velocity it is a simple matter of plugging into the equation for kinetic energy. The equation is KE=1/2mv^2 (you know this or you failed the test). In the model, the numbers would be KE=.5(7.32)(16)^2.
My solution is 948.0932659. If you are unsure of the above steps, you can now solve my problem before plugging in the numbers from your own homework.
I used to be able to do PHYSICS. This junk is pretty much gibberish to me now.