1. Agenda for the weekAgenda for the week  Today Wednesday Oct 31 st : Newton’s 2 nd law with lab, Bottle rocket lab due for 2 nd and 6 th periods ONLY  Tomorrow Thursday Nov 1 st : Friction with lab  Friday Nov 2 nd : Gravitational attraction, Kepler’s laws, and projectile motion with lab  Monday and Tuesday Nov 5 th and 6 th : Review for test, Bottle rocket lab due for 8 th period ONLY  Wednesday Nov 7 th : Fore and Motion unit test  Thursday and Friday Nov 8 th and 9 th : NO SCHOOL  Monday Nov 12 th : Egg drop lab due

3. Newton’s Second LawNewton’s Second Law  Force depends on mass and acceleration. Force = mass x acceleration (F = ma) Acceleration = Force / mass (a = F/m) 1. A force on an object will cause it to accelerate in the same direction as the force 2. This acceleration is directly proportional to the force 3. This acceleration is inversely proportional to the mass of the object

4. The science of NFL footballThe science of NFL football Newton’s Second Law video: http://science360.gov/obj/video/58e62534-e38d-430b- bfb1-c505e628a2d4/science-nfl-football-newtons-second- law-motion

5. Newton’s Second LawNewton’s Second Law  Force is expressed in Newton (N). It can also be expressed as 1 kg*m/s 2.  Mass is expressed in kilograms (kg).  Acceleration is expressed in meters per second per second or meters per second squared (m/s/s or m/s 2 ). It can also be any other unit of distance over time.

6. Calculations  If force is 20 N and mass is 10 kg, what is acceleration?  If force is 100 N and mass is 2 kg, what is acceleration?  If acceleration is 125 m/s 2 and force is 150 N, what is mass?  If acceleration is 80 m/s 2 and force is 250 N, what is mass?  If mass is 75 kg and acceleration is 28 m/s 2, what is force?  If mass is 115 kg and acceleration is 42 m/s 2, what is force?

7. Calculations  Mike’s car weighs 1,000 kg and it is out of gas. Mike is trying to push the car to a gas station and makes the car go 0.05 m/s 2. How much force did Mike apply to the car?  Joelle pushes with force of 10 N to her friend Jane who weighs 45 kg and is ice skating in front of her. What is Jane’s acceleration as a result of the push?

8. Calculations  A force of 150 N acts on a ball of mass 2 kg for 4 seconds. Find: a)the acceleration of the ball b)velocity at the end of 4 seconds  A force of 20 N acts on a body of mass 5 kg for 5 seconds. Find: a) the acceleration of the body b) velocity at the end of 5 seconds

9. Examples  Who has more force (given same acceleration)? Mr. Links or Miss Cho?  Which has more force? An elephant walking toward a mouse or a mouse sprinting toward the elephant?  Toy car demo

10. Examples  If you have a car with a mass of 500 kg and a constant velocity of 50 MPH and it hits a wall, what force will be applied to the wall?  When velocity is constant, there is no acceleration. Is it possible to have a force = 0 N?

11. Examples  If you throw a ball in space where there are no forces (gravity, friction, etc.) and you apply a 500 N force on a 2 kg ball, what is the acceleration?  What is velocity after 1 second? 2 seconds? n seconds?Can velocity approach infinity?  When you throw a ball on Earth, when is it traveling the fastest?