8. Tarzan grabs a vine 12 m long and swings on the end of it, like a pendulum. His starting point is 1.0m above the lowest point in his swing. What is the minimum speed that Tarzan must be moving when he grabs the vine if wishes to reach Jane who is situated across the river and 4m above the lowest point in the swing? Show all work. Tarzan 4m 1m 9. The figure below shows a roller coaster. The 500 kg cart is starting from rest at B and rolls along the track, past position D. At position D, it is clocked at 13m/s B D 35 m 20 m a. Complete the calculations to determine Ep and Ex at both positions (B and D). Show work. b. How much energy was "lost" overall from location B to D? Show work starting with Ebefore= Eafter. c. What is the efficiency of this cart in travelling from B to D? 10. A pole-vaulter of mass 75 kg reaches a maximum speed of 7 m/s just before he jams his pole into the notch to launch himself over the bar. Assuming that his pole is only 80% efficient, what is the maximum height that the pole-vaulter can reach