In the winter activity of tubing, riders slide down snow covered slopes while sitting on large inflated rubber tubes. To get to the top of the slope, a tube is pulled at a constant speed by a tow rope that maintains a constant tension force along the direction of the slope. When apply the following energy principle to this question, assuming the system is tube+earth+slope, which of the energy term is positive? Select all apply. K + Ug + Usp + Eth + Ech = Wexternal K Ug Usp Eth Ech Wexternal