Answer:
Work done is product of force and displacement
so maximum work is done in
4)A girl weighing 80 N goes up a flight of stairs that is 5.0 meters high carrying a box that weighs 0.5 N.
Explanation:
lets discuss all given cases
1)A girl weighing 70 N goes up a flight of stairs that is 4.0 meters high carrying a box that weighs 2.0 N.
here total force = 70 + 2 = 72 N
height = 4 meter
[tex]Work = 72\times 4 = 288 J[/tex]
2)A girl weighing 55 N goes up a flight of stairs that is 2.5 meters high carrying a box that weighs 1.0 N.
here total force = 55 + 1 = 56 N
height = 2.5 meter
[tex]Work = 56\times 2.5 = 140 J[/tex]
3)A girl weighing 60 N goes up a flight of stairs that is 3.0 meters high carrying a box that weighs 1.5 N.
here total force = 60 + 1.5 = 61.5 N
height = 3.0 meter
[tex]Work = 61.5\times 3 = 184.5 J[/tex]
4)A girl weighing 80 N goes up a flight of stairs that is 5.0 meters high carrying a box that weighs 0.5 N.
here total force = 80 + 0.5 = 80.5 N
height = 5 meter
[tex]Work = 80.5\times 5 = 402.5 J[/tex]
So maximum work in done in case 4
