Work is calculated as force multiplied by distance. Lifting an object weighing 200N through a distance of 0.5m would result in 100J of work. The main difference between using an elevator and stairs to go up is the time taken. Power is defined as the rate of doing work, or the amount of work done per unit of time. It is calculated as force multiplied by distance divided by time. The unit of power is the watt.

2. 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!

3. Calculating Work
•If you lifted an object weighing 200 N
through a distance of 0.5m, how much
work would you do?

4. 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.

5. Using
stairs………..
Using
Elevator………
..
What is the main difference between going up using an
elevator and using the stairs?
It is the “ Time “

6. When work done is related to time …….
WE call it

7. Power
•Power is the rate at which work is done
, or the amount of work per unit of
time.
…but a front-end loader can
do it in less time…
Two men can move a lot of sand using shovels…
…because the front-end loader has more POWER.

8. Power
•Power is the rate at which work is
done , or the amount of work per unit
of time.
•Power = work / time or
Because work = force x distance
•Power = force x distance / time

9. Power
•The unit for power is watt (W). One watt is equal
to 1 joule per second (1 J/sec).
•Large quantities of power are measured in
kilowatts (kW).
•One kilowatt equals _1_0_0_0_ watts.