Question

Circular Motion problem?

Answer 1

Please helpp me understand. This is the answer key and I am having a hard time getting through it.

Answer 2

wow.. a challenging problem.. first ll try to solve it myself. ok!

Answer 3

ok i got the solution.. its not tough.. but u really need to have understanding about

a) Energy conservation
b) Centripetal force and acceleration
c) Vector resolution

only then .. ll make an attempt to make u understand this :P

Answer 4

Can you help me understand the first line in the answer key? I can't seem to get why it is mga. Thank you.

Answer 5

Draw a diagram wil ya!

Answer 6

The speed of the mass when the string becomes vertical is:
(We use conservation of energy to find the speed. The energy is conserved since there are only 2 forces acting on the mass, the gravity being conservative in nature, and the tension which is perpendicular to the speed of the mass at all times and does not do any work.)
So, the potential energy at the horizontal position is converted to the kinetic energy when it reaches the bottom. So, mga=(mv^2)/2
potential energy at a height 'a' from the zero potential level(ground) is mga.
v=sqrt(2ga).
When the string reaches the peg, it starts a circular motion about A, since there is enough speed for circular motion with radius a-x.
Find v1^2 using conservation of energy and find T.