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25 Cards in this Set
- Front
- Back
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Newton's 3rd Law
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- For every action, there is an equal and opposite reaction
-If object A pushes on object B, the object B pushes back on object A with an equal and opposite force - Can't hit anything harder than it can hit you |
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Action- Reaction
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Action- reaction forces don't cancel becase they're acting on different objects
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Momentum
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- inertia in motion
- p=mv - units: kgm/s -related to Newton's 1st Law |
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Impulse
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- change in momentum
- I=^p=Ft -Related to Newton's 1st Law - a=F/m ^V/t=F/m m^v=ft ^p=Ft |
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Follow Through
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^p=Ft
^p- as big as possible F- same t- more time in contact - Make force last longer |
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Helmets and Air bags
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^p=Ft
^p- same F- Smaller when time is less t- longer with air bag |
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Law on Conservation of Momentum
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The total momentum of a system remains the same unless there's an outside net force.
Pbefore=Pafter The mometnum of a system stays the same unless a net outside force |
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Bouncing
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- bigger than ^p than stopping
- bounce is a double impulse |
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Momentum Concentration
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- Car and airplane crash
- Pbefore= Pafter |
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Work
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- How energy is transferred
- How an object gains and loses energy W=F//d //- parallel Nm= J |
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Energy
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- Ability to do work (E)
- Joules - circular definition |
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J
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Joules
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Types of Energy
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Mechanical Energy
- potential energy (PE) energy due to position (work done to put the object there) - Kinetic energy (KE) energy due to motion |
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Power
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- Rate of doing work, rate of transferring energy
P= w/t=E/t J/s= W (watts) 1 Watt- doing 1 J of work in 1 s |
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Potential Energy
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Walking vs. Running up stairs
Same energy ( same work to lift body to same height) - More power to run up PEgrav= work required to life object to that height =Fgravd =(mg)(h) |
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Ground level
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- Arbitrary Zero
- Path independent |
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Kinetic Energy
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KE= work needed to get up to speed
v=(fd) =1/2mv2 |
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Econs
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- The total amount of E in the universe always remains the same
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Useable Energy
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- KE
- PE - Electricity - Light - Chemical |
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Un-useble Energy
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- heat
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Sun
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- coal-dead plant- sun
- oil- dead animals-plants- sun |
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Heat Death
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- All energy transfers always involve a confersion of some energy to heat- spreads out and done with heat
- eventually it will all be heat |
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Gun Bullet Example
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Fgun=Fbullet
agun<abullet agun- becuase it has more mass- more inertia, resisting more change |
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Earth Acc
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- going towards earth
- earth coming up - small acc because of big mass |
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Changing speed
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-double the speed
- square the relationship (square KE) |
