Improvements

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# Improvements - PowerPoint PPT Presentation

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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## PowerPoint Slideshow about 'Improvements' - alvis

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Presentation Transcript
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)

• Alyssa pushes a 5.0 kg ball with a force of 22.5 N. What will the ball’s acceleration be?

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

OR

• Forces occur in equal and opposite pairs.
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?
Newton’s 3rd Law
• Identify force pairs
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?
Newton’s 3rd Law
• It can make stuff move!!
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?
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?
Newton’s 3rd Law
• In an action/reaction pair, why does one object sometimes accelerate while the other doesn’t?
Flyboard Video
• Flyboard
• What are the action/reaction forces?
Newton’s 3rd Law
• If they’re equal and opposite forces, why don’t action/reaction forces cancel out???

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.

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).
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
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

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.

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

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

Chuck Norris Fact
• When Chuck Norris does a push up, he’s not pushing himself up. He’s pushing the Earth down.
Newton’s 3rd Law
• Why don’t both objects have the same acceleration?
Video!
• Steve Spangler Newton’s 3rd Law Video 2:20 (propels himself using 3rd Law)

Shooting a gun

• Astronaut pushes off of spacecraft
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.
Bell Work