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# mechanics question watch

1. I'm really struggling with some mechanics questions and would really appreciate any help. Thanks guys.

1. Consider a circular orbit in the potential U(r) = ar² where r = radial distance. At t=0 a small radially directed impulse is applied to the particle so that the radial velocity instantly changes from 0 to v.
a.) What is the radius before the impulse is applied?
b.) Given that the impulse is small , what is the approximate radial position versus time r(t) for t>0 in terms of the variable t and the constants l,v, a and µ where l = magnitude of angular momentum?
c.)Is the orbit closed?
d.)Draw the shape of the new orbit.

If anyone knows of any good sites with notes on this subject please post the address in the thread! Thanks again.
2. You have missed out the definition of . Possibly it is the speed of the particle before the impulse is applied.

There also seems to be a silent assumption that the particle is of unit mass. Does your lecturer/text book usually assume that?
3. (Original post by Jonny W)
You have missed out the definition of . Possibly it is the speed of the particle before the impulse is applied.

There also seems to be a silent assumption that the particle is of unit mass. Does your lecturer/text book usually assume that?
That's my main cause of confusion. The question is word for word from an exam paper with no mention of µ. I was assuming that the particle was of a unit mass.

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