How do I show that the F acting on a particle moving in a circular path is always directed towards the origin? From what I understand I have to derive F using second derivative of the position vector and mass. How to show that it is pointing to the origin though?

Question

vincent-lyon.fr · Answer

This is true only if the path is travelled at constant velocity.
What you have to to is prove that acceleration is proportional to position with a minus sign.

wolfe8 · Answer

Right! I got that part. How would I then calculate the work done if the particle moves by 90 degrees along the circle? I know the formula is W = F * displacement * cos (theta)
How do I obtain the displacement equation?

vincent-lyon.fr · Answer

Whatever the angle moved is, simply remark that cos (90°) = 0

wolfe8 · Answer

Here is the full question. So is the work then just 0? I don't think I know how to do the rest either.

anonymous · Answer

i dont think work wont be zero..from a to b..work done is the product of centripetal force and the distance...

wolfe8 · Answer

Yeah so do I need to find the vector for displacement then? How?

anonymous · Answer

|dw:1379670540205:dw|  *b sinwt  so i guess distance vector should be sqrt(a^2+b^2)