A block of mass m = 3.40 kg is released from rest from point A

and slides on the frictionless track shown in the figure below. (Assume ha = 6.20 m.)

(a) Determine the block's speed at points B and C? in m/s... (Where hb = 3.20m) (Where hc = 2.0m)

(b) Determine the net work done by the gravitational force on the block as it moves from point A to point C? in J

without a diagram, I have to guess about the geometry...

I will guess that the block is at a height of 6.2m a tA, 3.2m at B, and 2.0m at C

if there is no friction, we use conservation of energy

going from A to B, the block loses PE in the amount m g (6.2 - 3.2) = 3.4 kg x 9.8m/s/s x 3m

loss of PE = 100J

this means the block picks up 100J of KE, and its speed will be 1/2 m v^2 = 100J

v = 7.67m/s

at C, the block has lost m g (6.2-2.0) J of PE

therefore

m g(6.2-2.0) = 1/2 m v^2

v = Sqrt[2 x g x 4.2m] = 9.07m/s

net work = change in KE = 1/2 x 3.4 kg x (9.07m/s)^2 = 139.9J

you could also calculate work = m g h = 3.4 kg x 9.8m/s/s x 4.2m = 139.9J