Finding the value of an unknown in a formula

Water flows out of a small hole in the side of a tank. When the surface of the water is \(h\) metres above the hole, the speed of the water leaving the hole is modelled by \(v=\sqrt{20h}\) m/s.

1. Find \(v\) when \(h=1.8\).
2. Find \(h\) when \(v=5\).
3. Find \(h\) when \(v=10\), and state how many times the depth in part (b) this is.