Replication, Multiplication, and Substitution.
Work = force * distance.
We must produce twice as much energy as we are lifting the weight twice as high.
But we are not increasing the force so we must increase the length of the ramp ( distance ) instead.
The new length will be twice as great as the previous length.
So 8 metres is required.
25 kg * 8 m = work = 100 kg * 2 m
In #8, the distance and the (magnitude of displacement) are equal, because he crawled in a straight line.
Displacement = (straight-line distance from start-point to end-point) in the direction from start to end, regardless of what route was actually followed.
Displacement = 5m, in the negative direction.
In #9 . . . distance will be the same. Displacement is going to be the same magnitude, but in the positive direction.
This is so simple that it's hard to talk about.
In #8, "What was the bug's distance ?". "Distance was 5 meters.". "What was the bug's displacement ?", "Displacement was 5 meters backwards."
In #9, What was the bug's distance ?". "Distance was 5 meters.". "What was the bug's displacement ?", "Displacement was 5 meters forward."
