You are given the mass of a child at 35kg. The child is sitting at the top of the slide that is 3.5m above the ground. You are required to find the potential energy of the child. Remember that potential energy is the energy resting at a particular position or configuration. It is equal to the mass of the object times its height times gravitational force. PE = mgh where PE is the potential energy, m is the mass of the object, g is the gravitational constant and h is the height.
PE = mgh
PE = (35kg) (9.8m/s^2) (3.5m)
PE = 1200.5 J