MeasuringMeasuringMotionMotion

SpeedSpeedVelocityVelocityAccelerationAcceleration

SpeedSpeedThe distance traveled The distance traveled by an object divided by an object divided by the time taking to by the time taking to travel that distancetravel that distance

SpeedSpeed Equation:Equation:Average Speed = Average Speed = total distancetotal distance total timetotal time SI Units:SI Units:*meters per second (m/s)*meters per second (m/s)*kilometers per hour (km/h)*kilometers per hour (km/h)*feet per second (ft/s)*feet per second (ft/s)*miles per hour (mi/h)*miles per hour (mi/h)

SpeedSpeed Example:Example:

Suppose a hot air balloon traveled Suppose a hot air balloon traveled 50 meters in 10 seconds. What is 50 meters in 10 seconds. What is the balloon’s speed?the balloon’s speed?

Remember – Speed is equal to Remember – Speed is equal to total distance divided by total total distance divided by total time.time.

VelocityVelocityThe rate of change of an The rate of change of an

object’s position over timeobject’s position over time

Velocity = Velocity = displacementdisplacement time time

Change in position means you Change in position means you must indicate a direction.must indicate a direction.

DisplacementDisplacement The The change in the object’s change in the object’s

positionposition compared to the compared to the starting point.starting point.

The difference between an object’s The difference between an object’s starting position and ending position.starting position and ending position.

Sometimes confused with distance Sometimes confused with distance which is the which is the total amount traveledtotal amount traveled

Graphing VelocityGraphing Velocity

Position-Time GraphsPosition-Time GraphsA change in an object’s position or displacement can be graphed over time using this Position-Time Graph.

Distance (m)

Time (s)

Constant Constant VelocityVelocity

When an object is moving at a constant velocity, it is moving the same distance for each time period.

This is shown on the graph using a straight line.

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The distance traveled or The distance traveled or displacementdisplacement does does not change over time.not change over time.

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AccelerationAcceleration The rate at which velocity changesThe rate at which velocity changes

An object accelerates if its speed, An object accelerates if its speed, direction, or both changedirection, or both change

An increase in velocity is called An increase in velocity is called positive accelerationpositive acceleration

A decrease in velocity is called A decrease in velocity is called negative accelerationnegative acceleration

AccelerationAcceleration Equation:Equation:

Average Acceleration = Average Acceleration =

final velocity – starting velocityfinal velocity – starting velocity time it takes to change velocity time it takes to change velocity

SI Units:SI Units:

*Velocity is expressed in m/s and time is *Velocity is expressed in m/s and time is expressed in seconds (s) expressed in seconds (s)

*Acceleration is expressed in m/s*Acceleration is expressed in m/s22

AccelerationAcceleration Example:Example:

A plane passes over point A at a A plane passes over point A at a velocity of 240 m/s north. Forty velocity of 240 m/s north. Forty seconds later, it passes over seconds later, it passes over point B at a velocity of 260 m/s point B at a velocity of 260 m/s north. What is the plane’s north. What is the plane’s average acceleration?average acceleration?