physics
posted by jack .
A 4.0 kg object is lifted 1.5 m. (a) how much work is done against the earth's gravity ? (b) repeat if the object is lowered insteadof lifted

The definition of work is (force) x (distance moved in the direction of the force)
(a) In this case, the force is M*g.
I assume that you know the value of g.
M is the mass. Complete the calculation.
(b) Change the sign of the previous answer. Negative work is done by whatever is lowering the weight. 
Answer

Force X Displacement
Force=mass X gravity
=> m g s
= 4 x 10 x 1.5
= 60 J