2. Work
•Work- A force acting through a distance.
•The distance that the object moves must be in
the same direction as the force applied to the
object.
Lifting Force
Movement Distance
What force is
having to be
overcome by the
lifting force?
Weight
3. Work• Work- A force acting through a distance.
• The distance that the object moves must be in the
same direction as the force applied to the object.
Pushing Force
Distance Moved
What force is
having to be
overcome by the
pushing force?
4. Lifting Force
Movement Distance
• Work is not done every time a force is applied.
• Work is done only when a force moves an object in
the same direction as the applied force.
Is the man doing work
when he lifts the box?
Yes.
Is the man doing
work when he holds
the box?
No!
Is the man doing
work if he carries
the box?
No!
(But he IS applying a force)
(But he IS applying a force)
5. Work
Think about pushing on wall that does not move.
A force is applied but the wall has not moved a
distance.
Is work
done?
6. WorkThink about pushing on wall that does not move.
A force is applied but the wall has not moved a
distance.
Is work
done?
No!
But I did expend
energy applying a
force!
7. Calculating Work
• Work = force (N) x distance (m)
• W = F x D
• The unit for work is a Joule (J).
• If you lifted an object weighing 1N through a distance
of 1m, you did 1 Joule of work:
W = FD = 1N x 1m = 1 J
Think about how much force a Newton is…about ¼ of a
pound. No!
8. Calculating Work
•If you lifted an object weighing 200 N
through a distance of 0.5m, how much
work would you do?
9. Calculating Work
•If you lifted an object weighing 200 N through
a distance of 0.5m, how much work would
you do?
Work = force x distance = 200 N x 0.5m = 100 J.
