A 0.40 kg block can slide up and down a rough 10-m-high, 30-m-long slope. At the bottom, a stiff spring with spring constant 800 N/m is compressed 0.50 m and used to launch the block up the slope. The friction force on the block from the slope is 1.2 N. What is the speed of the block when it reaches the top of the slope? When apply the following energy principle to this question, assuming the system is block+earth+spring+slope, which of the energy term is positive? Select all apply. K + Ug + Usp + Eth + Ech = Wexternal K Ug Usp Eth Ech Wexternal