How would i solve the following question?
A 14.8kg child sits in a 1.30kg swing. You pull the swing back, lifting it 52.1cm vertically, and let go. Determine the speed of the child and swing as the swing moves past its lowest point.

Question

How would i solve the following question?
A 14.8kg child sits in a 1.30kg swing.  You pull the swing back, lifting it 52.1cm vertically, and let go.  Determine the speed of the child and swing as the swing moves past its lowest point.

anonymous · Answer

what formula would i use?

ujjwal · Answer

1/2mv^2= mgh

anonymous · Answer

You can use law of conservation of energy.
Initially, P.Ei = 0, K.Ei = 0.

then, P.Ef = mgh
K.Ef = ? 

P.Ei + K.Ei = P.Ef + K.Ef
0 = mgh + K.Ef
you can find K.Ef and hence velocity.

anonymous · Answer

I would use conservation of energy. $$mgh = {1 \over 2} mv^2$$ where h is the height the child is raised (the lowest point of the swing is our reference point for potential energy, not the surface of the earth, I can explain this further if you don't fully understand.) and v will be the velocity at this lowest point.

ujjwal · Answer

my ans contd.. m cancels out itself so$$V=\sqrt{2gh}$$