After working on the handout’s first
column
Gravity = constant downwards acceleration.
Rate = 9.8 m/s per second (9.8 m/s/s)
[Trivia: 32 ft/s/s]
One more clicker question related to
“harder” problem.
Quick Quizzes 2.6, 2.7 with clickers (coming
in a few slides).
Quick Quiz 2.8 is a good question to help
you understand acceleration.
An object is tossed upwards into the air. On
the way up, what is the velocity?
1. Upwards (+)
2. Downwards (-)
3. Zero
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An object is tossed upwards into the air. On
the way down, what is the velocity?
1. Upwards (+)
2. Downwards (-)
3. Zero
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An object is tossed upwards into the
air. At the top, what is the velocity?
1. Upwards (+)
2. Downwards (-)
3. Zero
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An object is tossed upwards into the air.
After leaving your hand but while flying
upwards, which way is the acceleration?
1. Upwards (+)
2. Downwards (-)
3. Zero
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0
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0
An object is tossed upwards into the air. On
the way down, which way is the
acceleration?
1. Upwards (+)
2. Downwards (-)
3. Zero
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An object is tossed upwards into the
air. At the top, what is the acceleration?
1. Upwards (+)
2. Downwards (-)
3. Zero
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A tennis player on serve tosses a ball straight up.
While the ball is in free fall, does its acceleration:
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3.
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Increase the whole time
Decrease the whole time
Increase then decrease
Decrease then increase
Remain constant
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As the tennis ball travels through the air, its speed:
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2.
3.
4.
5.
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Increases the whole time
Decreases the whole time
Decrease then increase
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Remain constant
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Do first falling from tall building
question on handout
• Discuss next problem where ball is tossed
upwards. Before solving anything…
– ask the next clicker question
Will the speed when it hits the ground
be … than 60.38 m/s (when dropped)
1. Faster
2. Slower
3. Same speed
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What about being tossed
downwards?
• What changes in the formulas we did on
the board?
– Next clicker question.
Two objects are tossed. One is tossed upwards
+10 m/s. One is tossed downwards -10 m/s. Which
is moving fastest when it hits the ground?
1.
2.
3.
4.
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Upwards tossed object
Downwards tossed object
Both moving same speed
Not enough information given
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Ball landing on moving elevator
• Describe situation
• Ask class for written sentence or two, in
groups.
• Pick 3 groups to read answers aloud
• Before going over the answer, try next two
clicker questions
The instant before the ball lands on
the elevator, which is moving
faster?
1. Ball
2. Elevator
3. Same
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Which is the same for the ball &
elevator when the ball lands on
elevator?
1. Position
2. Velocity
3. Acceleration
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What’s the elevator’s acceleration?
1. -6 m/s
2. 0 m/s/s
3. -9.8 m/s/s
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