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Oomph!
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Homework Statement
I have a particle of mass m. The particle is moving in direction of axis z because of the gravitational force of a homogeneous circular disk of mass M and radius a. There is a formula for gravitational force of the disk on the picture.
Task:
1) Find the formula of potentional energy for z>0 (formula is on the picture).
2) We release the particle in z=4a/3. Find the velocity of impact on disk (formula is on the picture).
Homework Equations
Relevant equation is the formula for force of the disk. I just have to work with that.
The Attempt at a Solution
So, the first task is simple. I just have to integrate the force and i will get the formula of potentional energy. However, I don't understand why is important that z>0. And what about the constant? If I integrate, there is a constant C. I can just say, that C=0?
The second task is more difficult for me. I think that I have to compare kinetic energy (E=0.5mv2) and the potencional energy from first task. I have to substitute the z=4a/3 . I thought that the potentional energy at the beginning and the kinetic energy of impact on disk is same. However, probably not, because my formula was little bit different. Please, could you tell me what I have to do better?
Thank you.