physics not to har plez look?

Question

At a playground, a 18.0 kg child plays on a slide that drops through a height of 2.21 m. The child starts at rest at the top of the slide. On the way down, the slide does a nonconservative work of -312 J on the child. What is the child's speed at the bottom of the slide?

2.A particle moves under the influence of a conservative force. At point A the particle has a kinetic energy of 14 J; at point B the particle is momentarily at rest, and the potential energy of the system is 24 J; at point C the potential energy of the system is 6 J.
(a) What is the potential energy of the system when the particle is at point A?
J
(b) What is the kinetic energy of the particle at point C?

Answer 1

1)
In climbing the 2.21m up the slide, the child does work equal to mgh = (18.0)(9.8)(2.21) J = 390J. Gravity does this same amount of work on the child sliding down, and the slide does -312J of work on the child, leaving a net of 78J. This is in the form of kinetic energy. Kinetic energy = ½ mv²

So

½(18.0)v² = 78

Solve for v.

2)
A conservative force has the property that the sum of the potential and kinetic energies is constant. At point B, the particle is at rest and hence has no kinetic energy at that point.

Is that enough of a hint?