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Improvements

Improvements. Have students identify lots more force pairs & do more problems These last 3 sections…this hole chapter…is pretty disjointed  Use physics classroom online more!. Bell Work 5/8/13. Turn in lab if you’re done! (+1)

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Improvements

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  1. Improvements • Have students identify lots more force pairs & do more problems • These last 3 sections…this hole chapter…is pretty disjointed  • Use physics classroom online more!

  2. Bell Work 5/8/13 Turn in lab if you’re done! (+1) • Alyssa pushes a 5.0 kg ball with a force of 22.5 N. What will the ball’s acceleration be?

  3. Today you are going to…take notes on Newton’s 3rd Law of Motion. So you can…further understand forces & motion You’ll know you’ve got it when you can • State Newton’s 3rd Law • Identify force pairs • Give motion & no motion examples • Why don’t both objects always accelerate? • Why don’t both objects have the same acceleration? • Calculate accelerations.

  4. Newton’s 3rd Law • For every action force, there is an equal and opposite reaction force. OR • Forces occur in equal and opposite pairs.

  5. Newton’s 3rd Law • My hand pushes up on the eraser. • The eraser pushes down on my hand. • If the force on the eraser is 5 Newtons upward, what is the other force?

  6. Newton’s 3rd Law • Identify force pairs

  7. Newton’s 3rd Law • Cat-a-pult sitting on desk • Shuster pushing on wall • Hand pushing game! • Cat-a-pult launching golf ball • Which happens first?

  8. Newton’s 3rd Law • It can make stuff move!!

  9. Newton’s 3rd Law • Sarah pushes to the righton the wall. • The wall pushes to the left on Sarah. • If Sarah pushes to the right with 110 N of force, what is the magnitude and direction of the other force? • If Sarah is on roller skates and has a mass of 55 kg, what will her acceleration be? • What will the wall’s acceleration be? Why?

  10. Newton’s 3rd Law • Sarah pushes to the righton the wall. • The wall pushes to the left on Sarah. • If Sarah pushes to the right with 110 N of force, what is the magnitude and direction of the other force? • If Sarah is on roller skates and has a mass of 55 kg, what will her acceleration be? • What will the wall’s acceleration be? Why?

  11. Newton’s 3rd Law • In an action/reaction pair, why does one object sometimes accelerate while the other doesn’t?

  12. Flyboard Video • Flyboard • What are the action/reaction forces? • http://www.youtube.com/watch?NR=1&v=m4Bm3cs9TFo&feature=endscreen

  13. Newton’s 3rd Law • If they’re equal and opposite forces, why don’t action/reaction forces cancel out???

  14. Big Jim & Tiny Tina are ice skating close together. Big Jim says something Tiny Tina finds insulting. She pushes him with a force of 80.0 N. Calculate their acceleration.

  15. Who accelerates more? Why? Were the forces really equal and opposite?

  16. Newton’s 3rd Law on Ice • If Big Jim & Tiny Tina are ice skating. They push off from one another. Describe their acceleration. • They both experience the same force. • Tiny Tina accelerates more because she has less mass (inertia).

  17. Bell Work 4/22/13 • State Newton’s 3rd law. (c.s.) • Vinny kicks a board. Identify the pair of forces. • Why don’t action/reaction forces cancel out? • W5SAYWoS

  18. Schedule • Thursday • Newton’s 3rd Law notes • Friday • Newton’s 3rd Law notes • Monday • Finish Newton’s 3rd Law notes • Newton’s 3rd Law questions (homework) • Tuesday • Review Newton’s 3rd Law questions • Begin Racecar Project • Wednesday • Build racecar • Thursday • Test racecars • Friday • Newton’s 3rd Law quiz • Work, power, & machines

  19. Bill and Sarah are ice skating. Bill has a mass of 155 kg and Sarah has a mass of 65.0 kg. Sarah pushes off of Bill with a force of 88.0 Newtons. Calculate Bill’s acceleration AND Sarah’s acceleration. In the above problem, Bill and Sarah started off standing still, so their initial velocity was 0 m/s. If Sarah pushed for 0.400 seconds, calculate her velocity & his velocity using the acceleration equation.

  20. Newton’s 3rd Law • Allison pushes downon the ground. • The ground pushes upon Allison. • If Allison pushes with 603.4 N of force, what is the magnitude and direction of the other force? • If Allison has a mass of 61 kg, what will her acceleration be? • What will the Earth’s acceleration be? mass of Earth = 5.9742 × 1024 kilograms

  21. If Allison pushes with 603.4 N of force, what is the magnitude and direction of the other force? • If Allison has a mass of 61 kg, what will her acceleration be? • What will the Earth’s acceleration be? mass of Earth = 5.9742 × 1024 kilograms

  22. Chuck Norris Fact • When Chuck Norris does a push up, he’s not pushing himself up. He’s pushing the Earth down.

  23. Newton’s 3rd Law • Why don’t both objects have the same acceleration?

  24. More or Less?

  25. Video! • Steve Spangler Newton’s 3rd Law Video 2:20 (propels himself using 3rd Law)

  26. Shooting a gun • Astronaut pushes off of spacecraft

  27. Why don’t both objects have the same acceleration? • Forces occur in equal and opposite pairs. • They don’t cancel out because the forces are acting on two different objects. • The result of the forces is not the same because: • The objects have different masses, so the same force results in different acceleration. • There are often other forces acting on the objects.

  28. Bell Work • Sit in your seat & get your hw out.Schedule: • Collect HW • Review for tomorrow’s quiz • Launch cars • Distance to beat is 15.9 m

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