Do Now

1. Do Now • Complete IOD 402 handout • When finished, turn over. • Start a new notes page (with header) and copy down the definitions for all BOLD words in Ch. 5. • Air resistance • Inversely • Newton’s second law • pressure

2. Grade Do Now • Pass 1 person to your left…

3. Unit 1 Exam Results! • There are still a couple of people who need to make up the exam, so I can’t hand you back your test quite yet… but here are the results… • A1 – 72% B1 (8+27.3)/45 • A2 – 70% B2 (7.5 + 25.9)/45 • A3 – 69% B3 (30.1 + 8.5)/45 • You all did great! I’m so proud of you!! 

4. Newton’s 2nd & 3rd Laws Unit 2 Day 3 Oct. 3/4 , 2012

5. Today’s Objectives • SWBAT explain Newton’s 2nd and 3rd laws. • SWBAT give examples of Newton’s 2nd and 3rd laws.

6. Newton’s 2nd Law • F = ma • Force = mass x acceleration • Units • Force is in Newtons (N) • Mass is in kilograms (Kg) • Acceleration is in m/s2

7. Practice… • How much force is needed to accelerate a 1400 kilogram car 2 m/s2? • Write your GIVEN and UNKNOWN • Write the EQUATION • SUBSTITUE numbers for the letters in the equation • SOLVE for the unknown

8. Practice… • How much force is needed to accelerate a 1400 kilogram car 2 m/s2? • Write your GIVEN and UNKNOWN • a = 2 m/s2 m = 1400 Kg • Write the EQUATION • F = m x a • SUBSTITUTE the numbers for letters in the equation • F = 1400 kg x 2 m/s2 • SOLVE for the unknown • F = 2800 N

9. Practice… • How much force is present when a 2000 Kg elephant is falling with an acceleration of 40 m/s2? • Write your GIVEN and UNKNOWN • Write the EQUATION • SUBSTITUTE the numbers for letters in the equation • SOLVE for the unknown

10. Practice… • How much force is present when a 2000 Kg elephant is falling with an acceleration of 40 m/s2? • Write your GIVEN and UNKNOWN • a = 40 m/s2 m = 200Kg • Write the EQUATION • F = m x a • SUBSTITUTE the numbers for letters in the equation • F = 2000 kg x 40 m/s2 • SOLVE for the unknown • F = 80000 N

11. Practice… • How much force is present when a 300 Kg shoe is falling from the sky with an acceleration of 9.8m/s2? • Write your GIVEN and UNKNOWN • Write the EQUATION • SUBSTITUTE the numbers for letters in the equation • SOLVE for the unknown

12. Practice… • How much mass is needed for a car to have a force of 40 N with an acceleration of 25 m/s2? • Write your GIVEN and UNKNOWN • Write the EQUATION • SUBSTITUTE the numbers for letters in the equation • SOLVE for the unknown

13. Practice… • How much mass is needed for a truck to have a force of 200N with an acceleration of 10.2m/s2? • Write your GIVEN and UNKNOWN • Write the EQUATION • SUBSTITUTE the numbers for letters in the equation • SOLVE for the unknown

14. Practice… • How much acceleration is needed for a 7000 kg semi truck to have a force of 400 N? • Write your GIVEN and UNKNOWN • Write the EQUATION • SUBSTITUTE the numbers for letters in the equation • SOLVE for the unknown

15. Practice… • Complete # 19 - 21 on page 72 in your book.

16. Newton’s 2nd Lawproves that different masses accelerate to the earth at the same rate, but with different forces. • We know that objects with different masses accelerate to the ground at the same rate. • However, because of the 2nd Law we know that they don’t hit the ground with the same force. F = ma 98 N = 10 kg x 9.8 m/s/s F = ma 9.8 N = 1 kg x 9.8 m/s/s

18. Newton’s 3rd Law • For every action, there is an equal and opposite reaction

19. Newton’s 3rdLaw According to Newton, whenever 2 objects interact with each other, they exert forces upon each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body.

20. Newton’s 3rdLaw Flying gracefully through the air, birds depend on Newton’s third law of motion. As the birds push down on the air with their wings, the air pushes their wings up and gives them lift.

21. Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. In turn, the air reacts by pushing the bird upwards. • The size of the force on the air equals the size of the force on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards). • Action-reaction force pairs make it possible for birds to fly.

22. Other examples of Newton’s 3rd Law • The baseball forces the bat to the left (an action); the bat forces the ball to the right (the reaction).

23. Other examples of Newton’s 3rdLaw • Consider the motion of a car on the way to school. A car is equipped with wheels which spin backwards. As the wheels spin backwards, they grip the road and push the road backwards.

24. Drawing Force Diagrams • Force Diagrams are also called, Free Body Diagrams… • Practice drawing a diagram of a person sitting in a chair.

25. Drawing Force Diagrams Practice drawing a diagram of a bird flying in the air.

26. Drawing Force Diagrams Practice drawing a diagram of a bat hitting a ball.

27. Practice… • First… Finish putting your Ch. 5 vocabulary in your notes if you haven’t already. • Second… work on questions #1 – 10 on page ____ in your notes.