Question

A particle of mass m is moving in horizontal circle of radius r under a centripetal force =kr^2 where k is constant . what is the total energy of particle

Answer 1

I will tell you a trick to these type of question. Wherever you’ll study about total, potential and kinetic energy, you’ll always find that -

[potential energy] = 2*[total energy] = -2* [kinetic energy].

Now in this question, you need total energy. So, if you are able to find out the potential energy, then you can solve this question by relation given above.

Now the force is given as -k/r^2. So, we know that :

F = -dU/dr

So dU = -F.dr

From this, you can integrate force and you’ll get k/r.

Now using above relation, the total energy would be possibly k/2r.

I hope this would be the answer.