Physics II Day 10
Velocity and Acceleration
Velocity is
the speed of an object in a certain direction.
How
is it any difference from speed? Example: You and your friend walk 10 miles per
hour for an hour in opposite directions. You walked the same distance and the
same speed, but you are not in the same place
In
everyday life, we use accelerate to mean something is speeding
up. Scientifically,
acceleration is a change in speed, direction,
or both
OR the rate at which motion changes.
To decide if an object is accelerating or
not:
1)
Visualize it!
2) Ask yourself: Is it moving? If it is not, it is not accelerating.
3)
Ask yourself: Has it started
covering a greater (or shorter) distance in the same amount of time? If it is, it is accelerating.
4)
Ask yourself: Is it turning?If
it is, it is accelerating.
Let’s Try as a Class
Example 1: Slamming on your brakes and going from 70 mph to 0 mph
in 13 seconds.
It is ________________________________ because
____________________________
________________________________________________________________________________________________.
With a Partner 1: Going 70 kilometers per hour straight down a
highway for 3 hours.
It is ________________________________ because
____________________________
________________________________________________________________________________________________.
With
a Partner 2: A ballerina skating in a circle.
It is ________________________________ because
____________________________
________________________________________________________________________________________________.
Partner Challenge – TPWS - (Think for two minutes, discuss for two
minutes)
In the graph to the left, is the object accelerating? HOW DO YOU
KNOW?
____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________
On Your Own: Is it Accelerating?
1) A bicycle making a left turn.
It is ________________________________
because ____________________________
________________________________________________________________________________________________.
2) Shamyia runs the 500-meter dash. She
starts off only running 2 meters per second, but halfway through the race she
is running 9 meters per second.
She is ________________________________
because ___________________________
________________________________________________________________________________________________.
3) A swimmer swims across a pool at a rate of
5 meters per second.
He is ________________________________
because ____________________________
________________________________________________________________________________________________.
4) In a traffic jam, Ms. Hamam drives 30 mph
for 10 minutes, 15 mph for 20 minutes, then 40 mph for 5 minutes.
Her car is ________________________________
because _____________________
________________________________________________________________________________________________.
5) This graph above shows a bullet train’s motion.
Is it accelerating?
It is ________________________________
because
________________________________________________________________________________.
6. The graph below shows the motion of a
skateboarder. Is the skateboarder accelerating between 1 and 5 seconds?
It is ________________________________
because ______________________________________________________________________________.
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