1. Forces and Motion
2013 M.B. Pardington, BPS

2. PART 1

3. A force is a…
PUSH
PULL

4. A force can change the motion of an object.
DIRECTION
SPEED

5. A force can change the motion of an object.

6. An additional force in the same direction increases the speed of the object.
Push
Push + Push

7. An additional force in the same direction increases the speed of the object.
Push
Push + Pull

8. An additional force in the same direction increases the speed of the object.
Pull
Pull + Pull

9. Definition of Balanced Forces (add this to your paper )
are two forces acting in opposite directions
on an object, and equal in size.
Anytime there are balanced forces on an object,
the object stays still or
continues to move at the same speed
and in the same direction.

10. Opposing forces of equal magnitude acting on an object produce no change in motion.
5 N vs N
Cart doesn’t move.

11. Opposing forces of equal magnitude acting on an object produce no change in motion.
5 N vs. 5 N
Cart doesn’t move.

12. Definition of Unbalanced Forces (add this to your paper )
are two forces acting oppositely on an object, unequal in size, so they
cause a change in the motion
of an object.

13. NET FORCE 2 N PUSH to the RIGHT
Opposing forces of unequal magnitude acting on an object result in a change in motion.
NET FORCE 2 N PUSH to the RIGHT
3 N Pull + 5 N Push

14. NET FORCE 2 N PUSH to the RIGHT
A change in motion is described as a change in speed and/or direction of an object.
NET FORCE 2 N PUSH to the RIGHT
3 N Pull + 5 N Push

15. Forces must be balanced in order to achieve constant speed.
BALANCED FORCES
Forces must be balanced in order to achieve constant speed.

16. UNBALANCED FORCES
Forces must be unbalanced (nonzero net force) in order for an object to change speed and/or direction.
20 N
40 N

17. UNBALANCED FORCES
A force must be unbalanced (nonzero net force) in order for an object to change speed and/or direction.
30 N
20 N
50 N

18. UNBALANCED FORCES
A change in the mass of the object will result in a change in speed and/or direction of the object. Compare these 3 carts.

19. UNBALANCED FORCES
A change in the mass of the object will result in a change in speed and/or direction of the object. Compare these 3 carts.

20. UNBALANCED FORCES
A change in the mass of the object will result in a change in speed and/or direction of the object. Compare these 3 carts.

21. Speed is the ratio of distance covered per unit of time.
Speed = distance / time
The cart moved
6 meters per 3 seconds

22. Speed The cart moved 6 meters per 3 seconds
Mathematically, that’s 6 / 3 or 6 ÷ 3
which equals 2.
The cart moved
6 meters per 3 seconds
So, the cart moved 2 meters per second
or 2 m/sec

23. PART 2

24. FORCE
NON-CONTACT
CONTACT

25. Contact Force

26. A contact force is a push or pull that directly touches the object..

27. Friction WATER AIR OBJECTS
Friction is a contact force exerted between objects such as:
WATER
AIR
OBJECTS

28. Non-Contact Forces
MAGNETISM
GRAVITY
ELECTRICAL
CHARGES

29. These are pushes and pulls
Non-Contact Forces
These are pushes and pulls
from a distance.

30. Gravity
Gravity is a force of attraction between any mass and the matter near it. The larger the mass of an object, the greater the gravitational force it exerts on other objects. For objects on Earth, the pull of the Earth is the strongest force acting on them.

31. Gravity
“Jupiter is the most massive planet in our Solar System and; therefore, the gravity of Jupiter is the most intense in the Solar system. Its gravitational pull is 2.5 times what is here on Earth.”

32. Gravity

33. Magnetism S S N N
Here are “like” poles. Are they showing an attraction or are they repelling?

34. Magnetism N S S N
Magnetic Repulsion
They are repelling.

35. Magnetism N S N S
Here are “unlike” poles. Are they showing an attraction or are they repelling?

36. They are showing an attraction.
Magnetism N S N S
Magnetic Attraction
They are showing an attraction.

37. They pull and push without contact.
Magnetism N S N S S S N N
The attracting and repelling magnetic forces illustrate non-contact forces.
They pull and push without contact.

38. Check out these examples of magnetic pushes and pulls:
* See the side of the box for examples of how to use this device.

39. Check out these examples:
* Do not place the hourglass on magnet if the bottom is full. Place
Hourglass on magnet with the filings in the top bubble.

40. Check out these examples:

41. Check out these examples:

42. Wind Sock Demonstration
Electrical Charges
push
pull
Wind Sock Demonstration

43. They pull and push without contact.
Electrical Charges
The attracting and repelling electrical forces illustrated in the wind sock demonstration show non-contact forces.
They pull and push without contact.

44. Bibliography http://powerup.ukpowernetworks.co.uk/media/22576/78.jpg