What can you say about the snowboarder’s kinetic energy as he moves? -similarly, what can you say about the potential energy of the snowboarder? -based on your observations, what can you say about your prediction in parts a and b above concerning the potential and kinetic energy?

  His kinetic energy increases, potential energy decreases

  The sum of kinetic and potential energy is a constant at any instant before he comes to rest.

Explanation:

  Snowboarder is starting from a height and moving to the down direction. As he moves down his velocity increases, we know that kinetic energy is given by the expression , so as he moves his kinetic energy increases.

  When the snowboarder is starting his potential energy is maximum(Potential energy = mgh), as he comes down his potential energy decreases.

  Based on this we can conclude that the sum of potential energy and kinetic energy is a constant at any instant for a snowboarder before he comes to rest.

                             mgh+= Constant

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.