Unit 2 Class Notes

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Unit 2 Class Notes
The Kinematics Equations (1D Equations of Motion)

• Honors Physics

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Day 7
Review for test
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Step 1
Write Down What You Have (Look for Key Words)
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Coming to a stopStarting from
restCoastingMaximum HeightDropped
v2 0
v1 0
v1 v2 constant
v2 0
a -9.8 m/s2
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Slowing DownBrakingSpeeding
upAccelerating from rest
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Step 3
Solve the Equation
Step 4
Make sure your answer makes sense
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Some Helpful Tips From the Master
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Helpful Tip 1
Choose your Key Points in every problemand do
so wisely.
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Free-fallThrow up
Vertical Problems
Throw-downs
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v1 0
1
v1 0
2
2
2
v2 0 (at top)
1
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Throw up / Come Down (throw and catch at same
height)
Vertical Problems
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v2 0 (at top)
Dt12Dt23
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v1 -v3
1
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Throw up / Come Down (throw and catch at
different heights)
Use
and solve quadratically for t
Dx13
Dx13 -
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Helpful Tip 2
Assign positive and negative to different
directions.
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Helpful Tip 3
When solving a quadratic equation, do so with
minimal effort.
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Solving a quadratic equation
Choice B
Choice A
Factoring
Unlikely on a physics problem ?
Choice C ?
2nd Trace ? Zero (on graphing calculator)
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Helpful Tip 4
Get out of the habit of trying to use Chris
Farley when Leonardo is necessary.
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d rt(Can be used only at constant speed)
Can be used at constant speeds (a0) or when
accelerating. Awesome Dude!
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Helpful Tip 5
When dealing with a chase problem, use New-Look
Leo (built for the chase)
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Chase Problems
Since the two objects (A and B) end up at
the same position by the end of the chase, use
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But what if
The objects start at different places?
Its already accounted for here and here ?
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But what if
The objects start at different TIMES?
Youll need to use an extra equation relating the
two times. Plug this new equation into the long
equation above.
Example tA tB 1
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Helpful Tip 6
It is always important to remember that when
something is thrown up or down (or simply falls),
the acceleration at ALL times is constant.
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The acceleration of the ball at EVERY point on
this red path (When its rising up, when its
stopped, when its falling down) is always -9.8
m/s2.

-
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• An object thrown up has a constant acceleration
  at ALL times.

.the acceleration due to gravity
x
Objects rise and fall in the same amount of time
(assuming no parachute ?)
t
v
t
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Your training is complete. Now go, have some hot
tea, and rest for the upcoming Unit 2 Test
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TONIGHTS HW
Complete Review Worksheet
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