An athlete stretches a spring an extra 28.6 cm beyond its initial length. how much energy has he transferred to the spring, if the spring constant is 52.9 n/cm?

Awater-filled u-tube manometer is used to measure the pressure inside a tank that contains air. the water level in the u-tube on the side that connects to the tank is 5 ft above the base of the tank. the water level in the other side of the u-tube (which is open to the atmosphere) is 2 ft above the base. determine the pressure within the tank.