Question

find the velocity of b and c

Answer 1

All you need to do is conserve energy.
potential energy at A and potential and kinetic energy at B and C (kinetic also because it's moving at that point).
At A potential energy is mgh
=5×5×10
=250

At B potential energy is mgh
=5×2.5×10
=125
kinetic energy is 1/2 mv^2
=1/2×5×v^2
2.5v^2
now conserve
250=125+2.5v^2
125=2.5v^2
50=v^2
therefore v is approximately 7

similarly do for C
hope you find this useful