1. Balanced and Unbalanced Forces

2. What is a force?
A force is a push or pull that causes an object to move, stop, or change direction
In physics, a force is anything that makes an object accelerate

3. Balanced and Unbalanced Forces
Forces occur in pairs and they can be either balanced or unbalanced

4. Thank you, Sir Isaac Newton!
What unit is used?!
NEWTONS (N)
Thank you, Sir Isaac Newton!

5. Balanced Forces Balanced forces do NOT cause CHANGE in motion
They are equal in size and opposite in direction

6. Examples of Balanced Forces

7. Moving Objects Can Be BALANCED, too!
IF the object that is moving continues to move at the same speed and in the same direction!!

8. What 4 forces keep an airplane In the air?
Wings keep an airplane up in the air, but the four forces are what make this happen. They push a plane up, down, forward, or slow it down. Thrust is a force that moves an aircraft in the direction of the motion. It is created with a propeller, jet engine, or rocket. Air is pulled in and then pushed out in an opposite direction. One example is a household fan. Drag is the force that acts opposite to the direction of motion. It tends to slow an object. Drag is caused by friction and differences in air pressure. An example is putting your hand out of a moving car window and feeling it pull back. Weight is the force caused by gravity. Lift is the force that holds an airplane in the air. The wings create most of the lift used by airplanes.

9. Unbalanced Forces An unbalanced force always causes a change in motion
They are UNEQUAL in size.
When unbalanced forces act in opposite directions you can find the net force
Net force
Magnitude
The difference between the two forces
Direction
Direction of the largest force

10. Unbalanced Forces Cause an object to speed up…
Cause an object to slow down…
Cause an object to CHANGE DIRECTION

11. Examples of Unbalanced Forces

12. Remember those balanced moving objects?!
They become UNBALANCED when they change speed (accelerate or move slower) OR change DIRECTIONS.
If a car is traveling at a CONSTANT SPEED, but turns (changes directions), it is still UNBALANCED!

13. Balanced or Unbalanced?
1. If speed remains the same, but direction changes…
2. If direction remains the same, but speed changes…

14. Balanced or Unbalanced?
1. If speed remains the same, but direction changes…
Answer: Unbalanced
2. If direction remains the same, but speed changes…
Answer: Unbalanced

15. Unbalanced Forces
10 N
3 N
3 N, right – 6 N, left = 3N, left

16. Unbalanced Forces
10 N
4 N
4 N, left – 10 N, right =
6N, right

17. Unbalanced Forces
5 N, right + 10 N, right =
15N, right

18. Balanced or Unbalanced Forces?