Alright, so what you are looking at is a conservation of energy problem. Total Mechanical Energy in a system where energy is conserved is always equal to the sum of the kinetic energy and the potential energy. The sum of the change in these two quantities is also equal to zero.
So, what quantities do you know? You are given that at 0, the initial potential energy is 0. So, all the energy of the system must be kinetic.
So, KE= 1/2mv^2. We also know that the Mechanical Energy is conserved, so, the initial KE (with the initial velocity) plus zero (the initial PE) is equal to the final KE minus the final PE. What you are solving for is the final PE. So, rearrange the equation. You are left with the initial KE minus the final KE. Does this look familiar? It is one of the definitions for PE-- negative Work.
So, it can also be said that Potential Energy is equal to negative Force times the distance. Recall Newton's Laws. Force is equal to mass times acceleration. So, your problem can again be rewritten as PE=-mass*acceleration*distance. You are given the mass (without units? That's odd... =p) and you are given the x and y components of the position. So, if you look at your x and y paths as a triangle what is your original position function? If you draw a triangle, you should be able to figure out the original function.
After you calculate this, you can figure out your starting coordinates and, thus, the distance travelled. Also, once you have the position function, you can derive the acceleration. (Or else, just multiple the coefficient in front of t^2 by 2.) Now, plug those numbers into PE=(-1)(m)(a)(d). Voila.
Of course, you could always skip over the triangle ordeal and figure out your initial coordinates. From here you can figure out your velocities. and use the Kinetic Energy formula. But, what fun is that? =p I think the later method is more accurate.
A particle with mass 6.4 is acted on by a conservative force moves along a path given by:
x=5.2*cos(2.2t)
y=5.9*sin(2.2t)
Find the potential energy of the particle at t = 1, x = 8.0, and y = 14.7 while assuming that the initial potential energy equals zero.
2 answers
Thank you this helped a lot.
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