Dolphins and other sea creatures can leap to great heights by swimming straight up and exiting the water at a high speed. A 200 kg dolphin leaps straight up to a height of 7.8 m . When the dolphin reenters the water, drag from the water brings it to a stop in 1.8 m . Assuming that the force of the water on the dolphin stays constant as it slows down.

a. How much time does it take for the dolphin to come to rest?
b. What is the force of the water on the dolphin as it is coming to rest?