1. Newton’s Second Law Section 3-1

2. Force and Acceleration The greater the force is that is applied to an object, the greater its acceleration. The greater the force is that is applied to an object, the greater its acceleration. F=ma F=ma Hi there from DerekAlan Kreutzfeldt Hi there from DerekAlan Kreutzfeldt

3. Force and Mass The acceleration of an object depends on its mass as well as the force exerted on it The acceleration of an object depends on its mass as well as the force exerted on it Throw a baseball and a softball Throw a baseball and a softball F=ma F=ma

4. Newton’s Second Law F = m a F = m a The net force acting on an object causes the object to accelerate in the direction of the force. The net force acting on an object causes the object to accelerate in the direction of the force. Force will be labeled in Newtons (N) Force will be labeled in Newtons (N) –Mass = kg –Acceleration = m/s 2

5. You are pushing a friend on a sled. You push with a force of 40 newtons. Your friend and the sled together have a mass of 80kg. What is the acceleration of your friend on the sled?

6. A tennis ball undergoes an acceleration of 5,500m/s 2. How much force would the tennis racket have to exert to give the ball this acceleration? The ball has a mass of.06kg.

7. Friction Force that opposes motion between two surfaces that are touching. Force that opposes motion between two surfaces that are touching. What happens to a skate board after you give it a push? What happens to a skate board after you give it a push? Why does it slow down and eventually stop? Why does it slow down and eventually stop? Would the type of surface make a difference? Would the type of surface make a difference?

8. Amount of Friction The amount of friction depends on two things. The amount of friction depends on two things. –Kinds of surfaces –Force pressing the surfaces together

9. Three types of Friction Static Friction Static Friction Sliding Friction Sliding Friction Rolling Friction Rolling Friction

10. Static Friction The friction between 2 surfaces that are not moving past each other. The friction between 2 surfaces that are not moving past each other. –Getting the object moving

11. Sliding Friction Force that opposes the motion of two surfaces sliding past each other. Force that opposes the motion of two surfaces sliding past each other. –Once you have the object moving, there is still friction.

12. Rolling Friction The friction between a rolling object and the surface it rolls on. The friction between a rolling object and the surface it rolls on. –Put sand on the ice when your car is stuck. –Usually much less than static or sliding friction.

13. Air Resistance Force that acts in the opposite direction to that of the object’s motion. Force that acts in the opposite direction to that of the object’s motion. Crumpled paper VS Flat paper Crumpled paper VS Flat paper Surface Area Surface Area Air Resistance depends on: Air Resistance depends on: –Speed –Size –Shape of object

14. Terminal Velocity The highest velocity that a falling object can reach. The highest velocity that a falling object can reach. The point where the forces acting on the object are balanced. The point where the forces acting on the object are balanced.