1. Forces
Mr. Krall

2. What is a force?

3. FORCE – Any push or pull on an object.

4. PUSHING FORCES

5. PUSHING FORCES

6. PUSHING FORCES

7. PUSHING FORCES

8. PUSHING FORCES

9. PULLING FORCES

10. PULLING FORCES

11. PULLING FORCES

12. PULLING FORCES

13. PULLING FORCES

14. Balanced forces – when all the forces on an object cancel each other and do not cause an object’s motion to change.

15. The rope will not move because the forces cancel each other out.
Balanced forces + = +
The rope will not move because the forces cancel each other out.

16. Unbalanced forces – When the forces on an object do not balance out and the object’s motion changes.

17. Unbalanced forces Hulk has more force than tree!
The forces are unbalanced, so the tree’s movement changes.

18. Net force – the combination of all forces acting on an object

19. The box below has many forces acting on it.
GRAVITY
PULLING
MAN PUSHING
MINI-MAN PUSHING
FLOOR
PUSHING

20. If the size of the arrow shows the strength of the force…
GRAVITY
PULLING
MAN PUSHING
MINI-MAN PUSHING
FLOOR
PUSHING

21. What is the net force on the box?
GRAVITY
PULLING
MAN PUSHING
MINI-MAN PUSHING
FLOOR
PUSHING

22. The up and down forces are equal strength and opposite direction...
GRAVITY
PULLING
MAN PUSHING
MINI-MAN PUSHING
FLOOR
PUSHING

23. So they cancel each other out.
GRAVITY
PULLING
MAN PUSHING
MINI-MAN PUSHING
FLOOR
PUSHING

24. The two men are pushing in opposite directions…
MAN PUSHING
MINI-MAN PUSHING

25. but the red force is larger (stronger) than the green…
MAN PUSHING
MINI-MAN PUSHING
Part of the red force will be used up cancelling the green…

26. The leftover red force is the net force on the box.
MAN PUSHING
If the net force is enough to overcome the box and mini-man’s inertia…

27. Then the box and mini-man will move in the direction of the net force.

28. Imagine we have two air jets,

29. The red jet blows air to the right.

30. The blue jet blows air up.

31. Let’s put a ping pong ball in the picture
Let’s put a ping pong ball in the picture. Press “Go Red” to activate the red jet.
GO RED

32. The ball went to the right because the red jet put a net force on the ball to the right.
GO RED

33. Here’s our ball again. This time, press “Go Blue” to activate the blue jet.
GO RED
GO BLUE

34. If we blast the ball with both jets, what will happen?
GO RED
BOTH
GO BLUE

35. Press “Both” to activate both jets.
GO RED
BOTH
GO BLUE

36. The ball went diagonally because the net force is driving the ball up and to the right.
GO RED
BOTH
GO BLUE