Kinematics One Dimension Part 1

8/11/2019 Kinematics One Dimension Part 1

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Kinematics in 1 Dimension

Understand and describe

constant velocity

situations.

Understand and describeaccelerated motion

situations.

Use kinematics equations

to solve motion problems.

By completing this course, you will:


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Kinematics in 1-D Concept Map

Physics

Motion

Studies

Previous content

New content

08 : 3/32

Kinematic

Equations

Described by

Constant

VelocityConstant

Acceleration

Math Skills

Utilizes


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Motion

Almost everything we witness in our everydaylives involves motion:


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Definition

Kinematicsthe mathematical description of

motion without any reference to the cause. The

cause of this motion will be described later.


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Vector Preview

Although vectors will be fully explained in a later

tutorial, a brief introduction is needed here:

A vector is a

quantity that

has magnitude,size, and

direction.

A scalar is a

quantity that has

only magnitude,

size.

Ex: Velocity,

displacement,

acceleration

Ex: speed,

distance,

temperature,

mass


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Similarities:

Velocityand speed are similar terms. They are

often used interchangeably. However, there is aslight difference:

SpeedScalar

Velocityincludes a direction with magnitude,

and speedis only a magnitude.

VelocityVector


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Vector Question

A car is traveling at a constant 60mi/hr in a circularpath.

Does it have a constant speed?

Yes

Does it have a constant velocity?

No, because it is constantly changing direction.

That is part of what velocity describes.


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Constant Velocity

Imagine that a toy train is moving along the tracksat a constant and steady rate. There is no

slowing or speeding in its motion.

This motion represents a constant velocity.


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Velocity Formula:

The velocity of this train can be found with:

t

dv

Velocity, m/s

Time elapsed,

sec

Distance

covered, m

Typical metric

units are listed,

but others can be

used.


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Average Velocity:

Sometimes the previous formula is written as:

total

total

t

dv

The bar above the v means average. If an

object moves with a constant velocity, theaverage velocity is the same value.

If an object changesits velocity, this

formula may be more

useful.


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Illustration not to scale

Constant Velocity Example:

If sun light takes about 8 minutes to go from the sun

to the earth, how far away from the sun is the earth?Hi n t: light travels at 186,000 miles per second!


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480secxsec

mi

186,000d

Constant Velocity Example:

If sun light takes about 8 minutes to go from the sun

to the earth, how far away from the sun is the earth?Hi n t: light travels at a constant 186,000 miles per

second!

t

dv

vtd

Rearrange

formula for

desiredvariable

480sec

1min

sec60minx8.0

milesx1089d6


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Instantaneous Velocity

Instantaneous velocity: Thespeed of an object at any

particular instant.

The average speed

and instantaneousspeed may not be the

same!

A car that gradually

speeds up more and

more has an

instantaneous speed

that always changes.


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Instantaneous or Average Speed?

If the police monitor your

speed with a radar gun, are

they checking your

instantaneous speed or

your average speed?

Instantaneous speed. They

would be interested innoticing if you exceed the

speed limit at any point in

time.


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Solution to Thought Question

This solution can be very easy, or very difficult,

depending on how you go about it.

Easy way: The bicyclists will meet in 1 hours time.

Since the bee is flying for 1 hour at 30 km/hr, itcovers a total distance of 30km.


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Assignment

Page 30 Problems # 3,4,5,9

Write work for all problems! Show formulas, math

work, units!

Odd numbered problem have answers in the back

of the book.

Kinematics One Dimension Part 1

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