1. STARTER Dummies are used in simulated car crashes to study what might happen to passengers in a real crash. They are fitted with a range of measuring devices that track the motion of the dummies throughout the crash. By analyzing the data, scientists learn how injuries occur and how they can be prevented. What forces act on the crash-test dummy to slow its forward movement?

2. Day 17

3. INQUIRY MINI-LAB Mini Lab Materials Yarn paper clips Answer Questions

4. NEWTON’S SECOND LAW Acceleration is produced when a force acts on a mass F = ma Acceleration: a measurement of how quickly an object is changing speed.

5. WHAT DOES F = MA MEAN? Force is directly proportional to mass and acceleration. Imagine a ball of a certain mass moving at a certain acceleration. This ball has a certain force. Now imagine we make the ball twice as big (double the mass) but keep the acceleration constant. F = ma says that this new ball has twice the force of the old ball. Now imagine the original ball moving at twice the original acceleration. F = ma says that the ball will again have twice the force of the ball at the original acceleration.

6. UNITS F net = m a 1 N = 1 kg m/s 2 The SI unit of force is the Newton. A Newton is about a quarter pound. 1 lb = 4.45 N

7. Large Force and Small Mass equal greater acceleration (movement). – For example, Hitting a Baseball or Throwing a Football NEWTONS 2 ND LAW FORCE, MASS, ACCELERATION

8. NEWTON’S 2 ND LAW FORCE, MASS, ACCELERATION Small Force and Large Mass equal little to no acceleration (No movement). For examples, A boulder rock and a person pushing it.

9. If you double the mass, you double the force. If you double the acceleration, you double the force. What if you double the mass and the acceleration? (2m)(2a) = 4F Doubling the mass and the acceleration quadruples the force. So... what if you decrease the mass by half? How much force would the object have now?

10. PRACTICE PROBLEMS: KWFL CHART FORCE Directions: Copy and answer the Force problems. You can do this with another partner. Using a KWFL. 1.An object with a mass of 100 kg accelerates at a rate of 2.4 m/s 2. What force is exerted on the object? 2.A rolling object accelerates at 4.3 m/s 2. The force on the object is 86 N. What is the mass of the object? 3.What is the force exerted by a 10 kg toy car accelerating at 3 m/s 2 ? 4.What is the acceleration of a 1000 kg truck with 4000 N driving it?

11. WEIGHT VS. MASS Mass is the amount of matter in an object. Mass is also a measure of the inertia of an object. Weight is the force of gravity acting on an object. Force example: An astronaut on the moon does not weigh the same as on Earth. However, his mass never changes. Let’s make a T-chart: Weight vs. Mass

12. Weightmass Based gravityGravity does not matter Changes with locationDoes not change with direction F w =mgAmount of matter in an object

13. WEIGHT

14. EXIT SLIP List three examples of Newton’s 2nd law. Make sure to turn in lab. Answer all questions thoroughly.