Why is it so hard to graduate?

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

If steel is more dense that lake water, why can a boat float

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.