Objectives:1.Be able to distinguish between distance and displacement2.Explain the difference between speed and velocity3.Be able to interpret motion graphs

Vocabulary

DistanceDisplacement

SpeedAverage speed

Instantaneous speedvelocity

Distance and Displacement

Distance: How far an object has moved. Measure in Meters (M)Displacement: the distance and direction of an

object’s change in position from the starting point.

Speed

• Speed: The distance an object travels per unit of time.

Speed = Distance (m)Time (s)

• Average Speed: the total distance traveled divided by the total time travel, even if the speed was changing.

Instantaneous Speed

• Instantaneous Speed: the speed at a given point in time.

Plotting a Distance vs. Time Graph

• Distance is plotted on the vertical axis (y-axis)• Time is plotted on the horizontal axis (X-axis)• A horizontal line is a speed of 0 m/s (stopped)• The slope of the line is equal to the speed of

the object

Velocity

• Velocity: includes the speed of an object and the direction of its motion.

Objectives: 1. Identify how acceleration, time, and velocity

are related2. Explain how positive and negative

acceleration affect motion3. Describe how to calculate the acceleration of

an object

Acceleration

Acceleration: is the rate of change of velocity.

It’s how fast an object is getting fasterAcceleration = Change in Velocity (m/s)

time (s)

Calculating Acceleration

1. First calculate the change in velocity. Final Velocity - Initial Velocity (Vf - Vi)

2. Divide the change in Velocity by the Time of the measurements.

Final Velocity - Initial Velocity (Vf - Vi)Time t

Practice Problem

What is the acceleration the Fastest Car in the World

Sport: 0 to 60 mph in 3.7 seconds

Initial speed = 0 m/hFinal speed = 60 m/hTime = 3.7 seconds = 0.00103 hours

60 m/h - 0 m/h = 58,252 m/h2

0.00103 hours• For every hour this car drives it’s speed will

increase by 58,252 m/h

Practice Problem for Positive Acceleration

A jet airliner starts from rest at the end of a runway and reaches a speed of 80m/s in 20 seconds.

What is its acceleration?Initial speed = 0 m/s Final speed = 80 m/s t= 20 seconds80 m/s - 0 m/s = 4 m/s2

20 sFor every second the plane went down the runway it’s speed will

increase by 4 m/s

Practice Problem for Negative Acceleration

A skateboarder is moving a constant velocity of 3 m/s and comes to a stop in 2 seconds.

What is its acceleration?Initial speed= 3 m/h Final speed= 0 m/s t= 2 sec0 m/s - 3 m/s = - 1.5 m/s2

2 sFor every second the skateboarder slows down he will

decrease his speed by 1.5 m/s