2. a person uses a fixed pulley to raise a 75-n object 40 m. the force exerted on the object is
120 n. what is the efficiency of the pulley?

Will you chech and finish these for me, because i am stumped with them.

If a tank filled with water contains a block and the height of the water above point a within the block is 0.8 meter, what is the pressure at point a?

The radius of an atom is closest in size to a