Transcript answers in PP

Motion and Speed
Answers to Fusion
Motion and Speed Answers
• Skip 1, 2, and 4—See J#5 Motion Vocabulary
• 3
– If an object changes its position, then it is IN
MOTION. It is also changing speed and velocity
according to the definitions of both.
– The speed of a car describes how fast it goes; how
much distance it has covered in a given amount of
time.
5- How would you describe where the
question is located on the page?
• Three paragraphs from the start of the page;
Four inches from the bottom; Toward the
bottom of the page above the straight lines;
Under the paragraphs with the caption “With
a Reference Point.” …to give just a few. YOU
needed at least TWO.
6-Go three blocks
south and one block
east.
7-Go one block west,
one block north, and
then two blocks
west.
*You were to use
directions (N, S, E,
W) and blocks! Did
you?
8- Come on….it’s a maze.
9-Difference between speed and average speed:
Speed measures how fast an object is moving at
a specific moment in time (Instantaneous Speed
from your other notes). Average speed
measures how far an object moves in a given
amount of time.
11-
12- Average Speed = Distance ÷ Time
S = 100m / 13.75s
Answer = 7.27 m/s
13—Note…speed is constantLinear relationship
14—What does the slope say about
the speed?
• Steeper lines = faster
• Flat lines = not moving! No distance is
covered while time elapses.
15-What happens in the graph?
From 0-1 second, the ATV moved 10 meters. Then, from 1-3 seconds it didn’t
move. Time elapsed, but no distance covered. From 3-4 seconds it moved 20
meters and then from 4-5 seconds the speed was constant and it moved another
20 meters. Where was it moving the fastest? From 3-5 seconds.
16-Average Speed of the ATV in graph
Distance = 50 meters
Time = 5 seconds
Distance ÷ Time = Speed
50 meters ÷ 5 seconds = 10 meters/second
Distance
covered in a
given amount
of time
Describes
how “fast”
something
goes
Distance
covered in a
given amount of
time
AND direction
18- A reference point is a location to which you
compare other locations---TRUE.
19- Distance traveled does not depend on the path
you take---FALSE.
20-To calculate speed, you first need to find the
mass of an object---FALSE.
21-Average speed is a way to describe the speed of
an object that may not always be moving at a
constant speed.---TRUE.
22- In the graph, the object is moving at a constant
speed---TRUE (it is a straight line showing a linear
relationship).
23—Amy’s average speed was faster than Ellie’s
because Amy went farther (distance) in the same
amount of time.
D
Distance
(m)
B
C
A
Time
(Seconds)
• Compare slopes from A-B, B-C, C-D
D
Distance
(m)
B
C
A
Time
(Seconds)
C-D is the fastest. I know this b/c the line is the steepest.
A-B is the second fastest, again, compare slopes.
B-C is not moving. Time elapses, but no distance is
covered.
Acceleration
• Velocity (speed) measures a rate of change in
position (distance/time).
• Acceleration measures a rate of change in
velocity (Velocity/time)….V2-V1/time.
#1
• A car taking a turn at a constant speed is
accelerating---TRUE. *Change in velocity due
to direction.
• If an object has low acceleration, it isn’t
moving very fast---FALSE. *Cruise control in a
straight line is one example.
• An accelerating car is always gaining speed--False. *Could just be changing direction for
example!
Didn’t do #2 or #4.
• #3-Moving around a center.
• #5-Two components of a vector are
magnitude and direction.
• #6-Units for acceleration---you should have
underlined: meters per second per second OR
in other words, meters per second squared
(m/s2)
• #7---velocity is unchanged from B-C!
B---8m/s, t= 1s
C ---8m/s, t= 2s
Velocity 2 (8m/s) – Velocity 1 (8m/s)
1 second
0/1 = 0 m/s2 Velocity is unchanged.
• #8—
A-B Velocity 2 (8m/s) – Velocity 1 (4m/s) ÷ 1 sec.
8-4/1
4 m/s2
Whole trip– (7 m/s-4 m/s) ÷ 3 s
3/3 = 1 m/s2
#9—Increase in velocity (underline) Positive
Acceleration.
– Decrease in velocity (underline) Negative
Acceleration.
Centripetal Acceleration
#10—What direction is the acceleration in centripetal acceleration, where
speed does not change and direction does? --Perpendicular to the direction
of motion.
In order for an object to execute circular motion - even at a constant speed the object must be accelerating towards the center of rotation.
How does centripetal acceleration feel in real life?
It feels like a force pushing you into the car door when turning.
It’s what keeps you in your seat on the rollercoaster, or
plastered against the wall in the gravitron.
The centripetal force (created by centripetal acceleration….circular
movement creates this) is the force that causes an object to move in a circle,
acting towards the center of the circle. In the case of a satellite the
centripetal force is gravity, in the case of an object at the end of a rope, the
centripetal force is the tension of the rope.