Answer:
Twice the work needed to lift the 20cm object
Explanation:
Work done is derived using the expression below;
Work done = Force x distance
For this problem, we are lifting through a vertical height;
Work done = mg x h
mg is the weight of the body;
Since both bodies have the same weigh;
W1 is the workdone to lift 20cm
W2 is the workdone to lift 40cm
For the first lift;
W1 = (mg) x 20cm
(mg) = [tex]\frac{W1}{20}[/tex]
For the second lift;
W2 = (mg) x 40cm
Since they both have the same weight
(mg) = [tex]\frac{W2}{40}[/tex]
Equating the two weights;
[tex]\frac{W1}{20}[/tex] = [tex]\frac{W2}{40}[/tex]
20W2 = 40W1
W2 = [tex]\frac{40W1}{20}[/tex] = 2W1
