Objectives:
1. Be able to distinguish between distance
and displacement
2. Explain the difference between speed and
velocity
3. Be able to interpret motion graphs
Vocabulary
Distance
Displacement
Speed
Average speed
Instantaneous speed
velocity
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 related
2. Explain how positive and negative
acceleration affect motion
3. 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 faster
Acceleration = 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/h
Final speed = 60 m/h
Time = 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 seconds
80 m/s - 0 m/s = 4 m/s2
20 s
For 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 sec
0 m/s - 3 m/s = - 1.5 m/s2
2s
For every second the skateboarder slows down he will
decrease his speed by 1.5 m/s