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Chapter 1, Section 1 Measuring Motion

- When an object changes position over time, the

object is in motion. - .

- Motion can be observed by using a reference

point. A reference point is an object that

appears to stay in place compared to a moving

object. This allows you to tell that the object

is in motion - Reference point Example trees, buildings,

Earths surface

- Speed is the amount of time it takes you to

travel a specific distance. - To calculate speed
- Average speed total distance
- total time
- The units for speed are m/s, km/h

Objects with speed

- Velocity is the speed of an object in a

particular direction.Velocity must include a

direction. - (north, south, left, right)
- To calculate velocity total distance

direction - total time

- Velocity is only constant if speed and direction

do not change. Constant velocity is the motion of

a - straight line.
- If there is a change in speed ( 15 m/s to 20 m/s)

or direction (east to west), the velocity will

change.

Rocket changing velocity

- To combine velocities, it depends on whether the

object is traveling in the same direction or

different direction. The result is the resultant

velocity. - Same direction add velocities together
- 10 m/s north 5 m/s north 15 m/s north
- Different direction Subtract velocities
- 15 m/s west 10 m/s east 5 m/s west

- Acceleration is the rate at which velocity

changes. If an objects speed or direction

change, its velocity changes. - An increase in velocity positive acceleration
- A decrease in velocity negative acceleration or

deceleration

Roller coaster have positive and negative

acceleration!

- To calculate acceleration
- Average acceleration final velocity-starting

velocity -

time it takes to change velocity - a Vf- Vi
- t
- Units for acceleration m/s2

- When observing a graph you can determine if

acceleration is positive or negative based upon

the slope. It the slope goes upward it is

positive acceleration. If the slope goes

downward, it is negative acceleration.

- Centripetal acceleration occurs when an objects

travels in circular motion. - Example the Earth rotating!