1. WHAT IS A
FORCE?????

2. A force is
a push…..
PUSH

3. PULL
… or a
pull

5. PULL

6. FORCES NOT FORCES
Weight Mass
Magnetism Inertia
Friction Speed
Gravity Acceleration
Thrust Velocity

8. FRICTION
When an object moves in one direction,
sliding past another object, friction
moves it in the opposite direction!

9. THRUST
Thrust is a strong
push that quickly
moves an object

10. Forces are measured in
units called Newtons (N)
100 N

11. NET FORCE is the combining
of ALL forces on an object
•Each person is putting a force on the rope!
•Combined, they have a net force!

12. Forces moving in opposite
directions are subtracted
20N 10N
NET FORCE ON THE CAR = 10 N

13. NET FORCE ON THE TOY = 15N

14. Forces moving in the
same direction are added
12 N
12 N
NET FORCE ON THE CAR = 24 N

15. Newton’s 1 st Law of Motion
Objects at rest remain at rest,
objects in motion remain in motion with
the same speed and direction,
unless acted on by an unbalanced force.

16. What is a balanced
force?

17. BALANCED FORCES
•All forces acting on an object are
equal and opposite in direction.
•Net force equals zero
•Causes no change in motion of the
object

18. 20 N 20 N
BALANCED
FORCES
NET FORCE = 0N
NO MOVEMENT!!!!!

19. 20N 20N
NET FORCE ON THE CAR= 0N
THERE WILL BE NO MOVEMENT!

20. UNBALANCED FORCES
•All forces acting on an object
are NOT equal
•The net force will NOT be 0 N
•There WILL be a change in
motion

21. •The force of the boys pushing on the car,
is greater than the force of friction.
•The forces are unbalanced.
24 N
FRICTION
4N
What is the NET FORCE?
Which direction will the car move?

22. 10 N
50 N

23. Which way is this
car going to move?
100 N
10 N

24. Objects at rest remain at rest until
acted on by unbalanced forces.
The apple is
at rest
GRAVITY
makes it fall

25. The soccer ball
remains at rest, until
someone exerts
thrust on it by
kicking it.

26. Objects in motion remain in
motion with constant speed and
in the same direction, until acted
on by an unbalanced force.

27. INERTIA- An object’s resistance
to a change in its path of motion
IN OTHER WORDS…INERTIA IS
WHEN AN OBJECT DOES NOT
WANT TO SPEED UP, SLOW
DOWN, OR CHANGE
DIRECTION!!!

28. When the bike hits the rock, it will stop.
INERTIA says the
boy will resist a
change
in motion and keep
moving.
He goes flying over the handle bars

29. The skateboarder is moving at a
constant speed and direction. He will
eventually stop because of the force
of friction acting on the wheels.
FRICTION

30. •The car is in motion, until acted
on by the wall.
•The wall has more force than
the car, so it will be stopped

31. The pitcher
throws a baseball
in a certain
pathway. The
batter exerts a
thrust on the ball
with the bat, and
the ball changes
direction.

32. When the baseball is hit by the batter, it flies in
the air. INERTIA says that it will stay moving in
the same path at the same speed. GRAVITY
forces the ball to change it’s path.

33. This plane has a constant airspeed.
•When a force •If a different force
(THRUST) is acted (DRAG) is acted on
on it, the airspeed it, the airspeed will
will increase, and decrease, and the
the plane will plane will slow
accelerate. down.