1. WORK (Explain)

2. Work Notes Set your paper up like this…
Formula for work
When is work done?
When a force does no work
Work or Naw?
Work practice problems

3. Work Notes Set your paper up like this…
Force, a review…
When a force does no work
Work practice problems
Backside folded in
(left)

4. Work Notes Set your paper up like this…
Formula for work
Simple Machines
Work or Naw?
Backside folded in
(right)

5. A FORCE is a push or pull on an object.
FORCE… a review
A FORCE is a push or pull on an object.
How Forces Affect Objects
Slow them down
Speed them up
Stop them
Start them
Change their direction
Change their shape 5

6. Force Force is measured in Newtons (N).
We will use a spring scale to measure force.

7. Is this man doing work?

8. Formula for work Work = Force x Distance W=Fd
The unit of force is NEWTONS (N)
The unit of distance is meters (m)
The unit of work is Joule (J)
Solving for Work: W=Fd
Solving for Force: F=W÷d
Solving for distance: d=W÷F 8

9. When is work “done”?
Work is ONLY done by a force, IF the force causes the object to MOVE in the direction of the force.
Objects that are at rest may have many forces acting on them, but NO WORK is done IF THERE IS NO MOVEMENT. 9

10. When a force does no work 10

11. Check your understanding…
ANSWER
“D”
A skating waitress carries a tray to a customer.
Is holding the heavy tray considered work?
Yes, because the tray and the waitress carrying the tray are better moving toward the customer
No, because skating reduces the amount of friction and makes the job easier.
Yes, because the waitress can cover the same distance faster by skating than walking
No, because the movement of the waitress and the force holding the tray up are in different directions 11

12. Work or Naw? Students recording data in a science notebook Naw!
A quarterback holding a football
A baby lifting a toy block
Work!
Moving a box with a ramp
Holding a box and carrying it across the room
Naw! (because the force is perpendicular to the motion) 12

13. W=Fd
Calculate: If a man pushes a concrete block 10m with a force of 20N, how much work has he done?

14. W=Fd
Calculate: If a man pushes a concrete block 10 meters with a force of 20 N, how much work has he done?
W=?
F=20N
D=10m
W=Fd W=(20N)(10m) W=200J

15. More Practice Write the following problems and solve
1) How much work is done when a force of 33N pulls a wagon 13 meters?
2) How much work is required to pull a sled 5m if you use 60N of force?
3) A student uses 75J of work to move a refrigerator with a force of 1000N. How far did the student move the refrigerator?
4) If you did 500J of work pushing a box 20m, how much force did you use? 15

16. Simple machines make work “easier” by decreasing either the force needed OR the distance.16

17. Inclined Plane An inclined plane is an even sloping surface.
Inclined planes make doing work easier!

18. Although it takes less force for car A to get to the top of the ramp, all the cars do the same amount of work.
A B C

19. When a force does no work Work practice problems
Force, a review…
When a force does no work
Work practice problems
Backside folded in
(left)
A FORCE is a push or pull on an object.
Force is measured in Newtons (N).
We will use a spring scale to measure force.
1) How much work is done when a force of 33N pulls a wagon 13 meters?
2) How much work is required to pull a sled 5m if you use 60N of force?
3) A student uses 75J of work to move a refrigerator with a force of 1000N. How far did the student move the refrigerator?
4) If you did 500J of work pushing a box 20m, how much force did you use?
Slow them down
Speed them up
Stop them
Start them
Change their direction
Change their shape

20. When a force does no work Work practice problems
Formula for work
When is work done?
When a force does no work
Work or Naw?
Work practice problems
NO WORK is done IF THERE IS NO MOVEMENT or If the force and the motion are not in the same direction.
1) How much work is done when a force of 33N pulls a wagon 13 meters?
2) How much work is required to pull a sled 5m if you use 60N of force?
3) A student uses 75J of work to move a refrigerator with a force of 1000N. How far did the student move the refrigerator?
4) If you did 500J of work pushing a box 20m, how much force did you use?

21. Formula for work Simple Machines Work or Naw?
Backside folded in
Simple machines make work “easier” by decreasing either the force needed OR the distance.
Inclined plane
Lever
Wedge
Screw
Pulley
Wheel & axle