A rollercoaster cart that has a mass of 4500 kg has 67.5 kJ (kilojoules), or 67,500 J (joules), of gravitational potential energy. What is its height above the ground?
PT.2
The same 4500 kg rollercoaster cart is moving with 63.0 kJ (kilojoules), or 63,000 J (joules), of kinetic energy at the
bottom of its biggest hill. What is its velocity?

It's a snowy day and you're pulling a friend along a level road on a sled. you've both been taking physics, so she asks what you think the coefficient of friction between the sled and the snow is. you've been walking at a steady 1.5m/s, and the rope pulls up on the sled at a 32 ∘ angle. you estimate that the mass of the sled, with your friend on it, is 65 kg and that you're pulling with a force of 80 n .