4. A skier of mass 50 kg does a jump as shown below. (note: PE = Potential Energy, Ep, while KE = Kinetic Energy, Ek) A KE=0 J PE=50 000 J B D KE=20 000 J KE=20 000 J PE=30 000 J PE=30 000 J F . . . . . . . . . . . . . . . . . 100 m 60 m KE=35 000 J E PE=15 000 J |30 m KE=50 000 J PE=0 J a) Calculate the speed of the skier at A (start with equation and show work): b) Calculate the elevation of the skier at B (start with equation and show work): c) Calculate the speed of the skier at D (start with equation and show work): d) Notice that the total mechanical energy (KE + PE) is conserved at all points of the skier's path (always adds to 50000J). If there was friction, the total energy would still add to J. Describe whether the PE and KE values listed would increase/decrease/stay the same with the addition of friction. Explain your choice. PE - KE