2. Created by: Faith Cohen/2009 Newton’s Second Law

3. VELOCITY The word scientists use to describe how fast an object is moving

4. Velocity is measured as: change in distance change in time a change in distance per change in time

5. What are some examples of objects that move at high velocities?

6. What are some examples of objects that move at low velocities?

7. Scientists have a special way to measure a change in velocity: Acceleration Acceleration is a change in velocity.

8. If you’re speeding up, you have positive acceleration. If you’re slowing down, you have negative acceleration. If you’re changing speed quickly, you have high acceleration. If you’re changing speed slowly, you have low acceleration. The Way Acceleration Works:

9. Example: High negative acceleration because you’re slowing down quickly. You’re driving along in your car and suddenly have to slam on your brakes for a red light. Is the acceleration high or low? Is it negative or positive?

10. High positive acceleration because you’re speeding up quickly. Example: It’s your first space takeoff. Suddenly the rockets fire and you’re on your way to the Space Center. Identify the acceleration.

11. Low negative acceleration because you’re slowing down slowly. Example: You’re driving down the highway when your car runs out of gas and you slowly roll to a stop on the side of the road. Identify the acceleration.

12. Low positive acceleration because you’re speeding up slowly. Example: You’re walking to class when you realize you’re running just a little bit late. You start walking a bit fast, but you still hope to make it on time. Finally the bell rings so you break into a jog and then a run, trying to get to class before the teacher notices you’re late.

13. If you’re driving a car and want to speed up, what do you do? If you’re riding a Big Wheel bike and want to go faster, what do you do? If you want to win the race and you are behind, what do you do?

14. Pushing pedals, pressing accelerators, and running are all examples of forces. 1) A force is anything that changes the velocity of an object. 2) A change in velocity is acceleration, so... therefore 3) A force is anything that gives an object acceleration.

15. Nothing will change speed unless acted upon by a force. If it’s sitting still, it will keep sitting still. If it’s moving fast, it will keep moving fast. Only a force can change the velocity of an object.