Opening Activity 1.Compare and contrast the following: Speed
and velocity Distance and displacement Average speed and
instantaneous speed 2.A cyclist must travel 800 km. How many days
will the trip take if the cyclist travels 8 h/day at an average
speed of 16 km/h?
Slide 3
3.2 Acceleration pp 76-80 Essential Questions How are time,
velocity, and acceleration related? How do I calculate the average
acceleration of an object? What is positive and negative
acceleration and how are they different?
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Acceleration, Speed, and Velocity p 76 When a car takes from a
stop, the cars velocity increases. It also accelerates.
Acceleration is the change in velocity divided by the time for the
change to occur
Slide 5
Acceleration, Speed, and Velocity p 76 When a car slows down
and stops, the cars velocity decreases. It also accelerates
(deceleration).
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Changing Direction p 77 Acceleration occurs when an object
changes its speed, its direction, or both. We now have three terms
that have magnitude (size) and direction; these are vectors. Name
the other two vectors we have covered
Slide 7
Changing Direction p 77 Any time a moving object changes
direction, its velocity changes and it is accelerating.
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Calculating Acceleration
Slide 9
Suppose a jet airliner starts at rest at the end of a runway
and reaches a speed of 80 m/s in 20 s. What is the planes average
acceleration?
Slide 10
v i = _____ v f = ______ t = _____
Slide 11
Suppose a jet airliner starts at rest at the end of a runway
and reaches a speed of 80 m/s in 20 s. What is the planes average
acceleration? v i = 0 m/s v f = ______ t = _____
Slide 12
Suppose a jet airliner starts at rest at the end of a runway
and reaches a speed of 80 m/s in 20 s. What is the planes average
acceleration? v i = 0 m/s v f = 80 m/s t = _____
Slide 13
Suppose a jet airliner starts at rest at the end of a runway
and reaches a speed of 80 m/s in 20 s. What is the planes average
acceleration? v i = 0 m/s v f = 80 m/s t = 20 s
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Now imagine that a skateboarder is moving in a straight line at
a constant speed of 3 m/s and comes to a stop in 2 seconds. What is
the skateboards average acceleration?
Slide 20
v i = _____ v f = _____ t = _____
Slide 21
Now imagine that a skateboarder is moving in a straight line at
a constant speed of 3 m/s and comes to a stop in 2 seconds. What is
the skateboards average acceleration? v i = 3 m/s v f = 0 m/s t = 2
s
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Opening Activity 1.It takes a car one minute (60 seconds) to go
from a dead stop to a speed of 40 m/s. What is the average
acceleration of the car? 2.A truck cruising at 50 m/s slams on its
brakes to avoid a collision, stopping in 3.5 s. What is the
acceleration of the truck
Slide 26
Opening Activity 1.It takes a car one minute (60 seconds) to go
from a dead stop to a speed of 40 m/s. What is the average
acceleration of the car?
Slide 27
Opening Activity 1.It takes a car one minute (60 seconds) to go
from a dead stop to a speed of 40 m/s. What is the average
acceleration of the car? t = 60s v i = 0 m/s v f = 40 m/s a =
???
Slide 28
Opening Activity 1.It takes a car one minute (60 seconds) to go
from a dead stop to a speed of 40 m/s. What is the average
acceleration of the car? t = 60s v i = 0 m/s v f = 40 m/s a = ??? =
(v f v i )/(t f t i )=(40-0)/60 = 0.67 m/s 2
Slide 29
Opening Activity 2.A truck cruising at 50 m/s slams on its
brakes to avoid a collision, stopping in 3.5 s. What is the
acceleration of the truck?
Slide 30
Opening Activity 2.A truck cruising at 50 m/s slams on its
brakes to avoid a collision, stopping in 3.5 s. What is the
acceleration of the truck? t = 3.5s v i = 50 m/s v f = 0 m/s a =
???
Slide 31
Opening Activity 2.A truck cruising at 50 m/s slams on its
brakes to avoid a collision, stopping in 3.5 s. What is the
acceleration of the truck? t = 3.5s v i = 50 m/s v f = 0 m/s a =
??? = (v f v i )/(t f t i )=(0-50)/3.5 = -14.29 m/s 2