2. Force and Net force

3. Force We learned about the motion of objects. That there are three types of motion: speed, velocity, and acceleration. Also, how to calculate speed: Speed= d/t But, what causes an objects motion? Forces create or prevent motion.

4. Force Force is a push or a pull Examples: gravity, friction, magnetic, electrical. Forces can be balanced or unbalanced. Balanced forces have no change in motion. Unbalanced forces create change in motion. Forces can be measured with a spring scale. Newton (N) is the unit of force.

5. Force Spring scale (N):

6. Examples of Balanced forces

7. Unbalanced forces

8. More Unbalanced forces

9. Net Force

10. The Net force is the sum (total) of all forces acting or applied to an object.

11. Net Force

12. Calculating Net Force When forces move in opposite directions you subtract to find the net force. Unbalanced forces creates motion/movement.

13. Calculating Net Force When forces move in opposite directions you subtract to find the net force. Balanced forces have no motion.

14. Calculating Net Force When forces move in the same direction you add to find the net force. Unbalanced forces creates motion/movement.

15. Force Arrows Forces can be shown with force arrows The size of and length of the arrow show its strength (magnitude). A longer arrow = A stronger arrow 30N 10N 100N

16. Any Questions?

17. Practice Problem Juan pushes a box with a force of 5N to the left. Brandon pushes the same box from the opposite side with a force of 3N to the right. What happens to the box? A. The box moves to the right with a force of 8N. B. The box does not move forces are balanced. C. The box moves to the left with a force of 2N. Answer: Forces are opposite and must be subtracted. 5N-3N = 2N towards the left (larger force)

18. Speed Problem Forces that act on objects can affect their speed and direction. A car is traveling down the street in direction A. Which of the forces shown in the figure above would affect ONLY the speed of the car? A. 1 B. 2 C. 3 D. 4

19. Speed Problem Forces that act on objects can affect their speed and direction. A car is traveling down the street in direction A. Which of the forces shown in the figure above would affect ONLY the speed of the car? A. 1 B. 2 C. 3 D. 4