When salmon head upstream to spawn, they may encounter a waterfall. If the water is not moving too fast, the salmon can swim right up through the falling water. Otherwise, the salmon jump out of the water to get to a place in the waterfall where the water is not falling so fast. When humans build dams that interrupt the usual route followed by the salmon, artificial fish ladders must be built.
They consist of a series of small waterfalls with still pools of water in between them (see the photo). Suppose the salmon can swim at 5.0 m/s with respect to the water. How fast will the salmon be swimming with respect to the ground when it starts swimming up the waterfall?

(a) What is the maximum height of a waterfall up which the salmon can swim without having to jump? 

(b) If a waterfall is 1.5 m high, how high must the salmon jump to get to water through which it can swim? Assume that they jump straight up. 

(c) What initial speed must a salmon have to jump the height found in part (b)? (d) For a 1.0 m high waterfall,