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# Interpreting Motion - PowerPoint PPT Presentation

Interpreting Motion. How to read a Velocity vs. Time graph. Velocity vs. Time Graphs. v. v. t. t. Constant velocity. Constant positive acceleration. Velocity vs.Time graphs. v. v. t. t. Constant negative acceleration but object has changed direction (WHY?).

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## PowerPoint Slideshow about ' Interpreting Motion' - jin-garrison

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### Interpreting Motion

How to read a Velocity vs. Time graph

v

v

t

t

Constant velocity

Constant positive acceleration

v

v

t

t

Constant negative acceleration but object has changed direction (WHY?)

Constant negative acceleration

If you want to know what the average acceleration is calculate the slope.

Slope = Δv / Δt = aave

Δv = vf - vi

Δt = tf - ti

Using slope to predict motion calculate the slope.

• On a velocity vs. time graph

• If slope is 0, then acceleration is 0. The velocity is constant.

• If slope is positive, acceleration is constant.

• If slope is negative, acceleration is constant in the opposite direction.

Is the object changing speed? calculate the slope.

• You must consider both the direction of the velocity and the direction of the acceleration.

• If velocity and acceleration are in the same direction object is speeding up.

• If the velocity and acceleration are in opposite direction object is slowing down.

Speeding up calculate the slope.

v

Is the velocity positive or negative?

+v

+a

Is the acceleration positive or negative?

t

0

-a

-v

The sign for a and v are the same so both objects are speeding up!

Slowing calculate the slope.down (deceleration)

v

Is the velocity positive or negative?

+v

-a

Is the acceleration positive or negative?

t

0

-v

+a

The sign for a and v are opposite so both objects are slowing down!

Finding calculate the slope.Displacement

• Equal to the “area under the curve” on a v vs. t graph

• Triangle A = ½ b×h

• Rectangle A = l×w

• Base and length are measured in s.

• Height and width are measured in m/s.

Area = (m/s)(s) = m

V (m/s) calculate the slope.

Area = l × w

length = 3 s width = 50 m/s

50

Δd=150 m

3s ×50 m/s

t (s)

1 2 3 4 5 6 7

-25

Velocity vs. Time Graphs calculate the slope.

• The slope of the line tells you the ____________ of the object.

• The “area under the curve” represents the change in position or ____________of an object.

displacement

acceleration

pg 93 #13,15-16 and section review #1-2,4 calculate the slope.