From our physics class, we know that Work is a product of
Force and Displacement. The force must be the force in the same direction with
the displacement. So force and displacement must be parallel.
A. How much work in J does the string do on the boy if the
boy stands still?
Since we know that: Work = Force * Displacement
and in this case displacement is equal to zero, therefore
Work must also be equal to zero.
Work = 0
B. How much work does the string do on the boy if the boy
walks a horizontal distance of 11m away from the kite?
Now are given a displacement of 11 m which is a horizontal
distance. Therefore we must first calculate the horizontal component of force:
Fx = 4.5 N * cos 30
Fx = 3.897 N
So work is:
Work = 3.897 N * 11 m
<span>Work = 42.87 J ~ 43 J</span>
