Physics Ch 8
Terms
undefined, object
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- Newton's 3rd Law
- For every action, there is an equal and opposite reaction- If Object A pushes on Object B, Object B pushes back on object A with an equal and opposite force
- Action
- Reaction forcxes don't cancel because they're acting on different objects
- Momentum
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inertia in motion
p=mv (vector)
related to Newton's 1st law
Units: kgm/s - Impulse
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change in momentum
I=^P=Ft
^= change in
Related to Newton's 2nd Law:
A= F/M
^v/t=F/m
m^v=ft
^p=Ft - Follow through
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makes force last koinger
^p=Ft
p= as big as possible
F= smae
t= more time on contact - Helmets and Air Bags
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^p=Ft
p= same
F= smaller when time is longer (less)
t= longer with air bag - Law of 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 - Bouncing
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bigger ^p than stopping
bounce is double the impulse - Momentum concentration
- Car collision example:
- Work
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How energy is transfered (how an object gains or loses energy)
W=F,,d
W= work
,,= parallel
d= distance
in direction of motion
circular definition with energy
Lift 1N object 1m high
W= (1N)(1m)= 1J
Nm= J
J = joules - Energy
-
ability to don work (E)
calculated in J - J
- Joules
- Types of Energy
-
mechanical
light
heat
sound
electromagnetic
ect... - Mechanical Energy
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Potential energy (PE) energy due to position
Kinetic Energy (KE) energy due to motion
PE Wdone to put the onject there - Power
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walking up stairs vs. running up stairs
same enrgy (same work to lift body to same height)
More POWER to run up
PEgrav= work required to lift object to that height
=Fgravd
= (mg)(h)
PEgrav= mgh - W
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Watts
60 W lighhtbult take 60 J of electric E and turnsd it into 60J of light and heat every second
1 W= doing 1 J of work every 1 second - Arbitraru Zero
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ground level
path independent - Kinetic Energy
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KE= work needed to get up to speed v= (fd)
KE= 1/2mv2