1. Chapter 2-3
Newton’s Second Law

2. How do forces change motion?
Changing the object’s:
Speed
Direction
Both

3. Velocity
Velocity: Speed in a given direction
Hurricane 3

4. 4

5. Unbalanced Forces on an Object at Rest
If the object moves – the forces are unbalanced
Moves in direction of net force

6. Unbalanced Forces on an Object in Motion
Speeding up
Slowing down
Changing direction
Acceleration (speed and direction)

7. Newton’s Second Law
The amount of force acting on an object equals the object’s mass times its acceleration. 7

8. Newton’s 2nd Law Force = Mass x Acceleration F = M x A A = F / M
M = A / F
Newton (N) – Unit of measurement for Force
1 Newton = 1 kg x 1 m/s² 8

9. 9

10. Newton’s 2nd Law
If you throw a softball and a baseball as hard as you can, why don’t they have the same speed? 10

11. 2nd Law Practice
What is the acceleration of a boy on a skateboard if the unbalanced forward force on the boy is 15 N? The total mass of the boy and the skateboard is 58 kg.
What force is necessary to accelerate a 1250 kg car at a rate of 40 m/s2?
What is the mass of an object if a force of 34 N produces an acceleration of 4 m/s2? 11

12. Circular Motion Example – 20 m/s to the north
Circular Motion – May have same speed, but not the same velocity 12

13. Centripetal Force
Force that acts perpendicular to the direction of motion
Goes towards center of curve

14. Satellites and Planet Motion
Moves in straight path – inertia
Gravity pulls object inward – centripetal force