Distance, Speeds and Forces and Motion 1.ppt

Motion, distance, speed, and velocity. Graphing motion. Time-distance graphs

1. Motion
•Define distance, speed and
velocity.
•Graph motion.
•Use measurement & time-distance
graphs to represent the motion of
an object in terms of its position,
direction or speed.

3. Motion
•Motion is a change in position of an object
with respect to time.
•The following terms are used to describe
and measure motion.
–Position
–Direction
–Speed

4. Position
•Position – the location of an object.
Change in position is measured by
distance (length of the path) moved from
one position (reference point) to another.
–What is a reference point?
Class demonstration: One volunteer and the rest of
the class is split into two groups. This activity will
illustrate the idea of a reference point.

5. Reference Point – is a place or object used
for comparison to determine if something is in
motion. An object is in motion if it changes
position relative to a reference point.

6. Direction
•Direction – is the relationship of the
position of a moving object to another
position.

7. Distance
•Distance-
- is the measure of “how much ground an
object has covered during its motion”
-is the total length of the path traveled
- Usually measured in meters

8. Displacement
•Displacement
is the straight-line distance from the starting
point to the ending point, including
direction

9. Speed
•Speed – is the rate of change in position
or “rate of motion”. How long it takes to
move from point A to B.
– Speed does not necessarily mean that
something is moving fast.

10. Average Speed
•The average speed of an object tells you
the (average) time at which it covers a
given distance.
–Average speed is the result of the total
distance divided by the total time taken.

11. Calculating Average Speed
(v = d/t)
•v = d/t where:
•v is the average speed of an object
•d is the distance or length of the path of
the object
•t is the time taken to cover the path
•Speed is measured using the following types
of units:
–meters per second (m/s)
–kilometers per hour (km/h)
–miles per hour (mph)

12. What is the difference between speed and
velocity?
Velocity is speed with direction

13. V=d/t
v
d
t
d=vt t=d/v

14. TO HELP SOLVE EQUATIONS, HERE IS A STEP BY STEP
GUIDE TO FOLLOW.
G U E S S
G – find your Givens
U – what is your Unknown (trying to find)
E – what is the Equation you need?
S – Substitute your givens
S - Solve

15. Examples:
•Calculate the speed of an object using the
following information:
t = 35 s and d = 50m
Step 1 – GUESS
Givens are t = 35 s and d = 50 m
Unknown: v
Equation: v = d / t
Substitute: v = 50 / 35
Solve: v = 50 divided by 35

16. Examples
•Suppose a cyclist travels 32 kilometers during
the first two hours of riding, and 13 kilometers
during the next hour. Calculate the average
speed:
-total distance = 32km + 13km
-total time = 2h + 1h
Average speed: 45km/3h = 15km/h or
15 kilometers per hour

17. Examples
•Use the speed equation to determine how
far an object traveled.
v=7m/s
t=3s
How far did the object travel?
Rearrange v=d/t
d=vt
d=7m/s(3s)
d=21m

18. 1.How long will it take to get to Atlanta, GA for a
Falcons game from Greenville, SC (145 miles or
233 km). You know you can travel about 70
mph?
2. If a bamboo plant grows 28 centimeters in 11
days, what was the average speed the plant
grew per day?
3. A soccer player was practicing on the soccer
field last week. He ran back and forth on the field
for a total of 750 yards. His average speed was
12 yards per second. How long did it take him to
finish?

19. Graphing Speed
•Do you think it is possible to represent
speed using a graph?
•If so, what type of graph would you use?
–Line graph, bar graph, circle graph????

20. •When graphing speed you would use a line
graph.
•A line graph shows the relationship between
distance and time and how it relates to
speed.
•The slope of the line gives us information
about the speed and direction of an object.

21. •You graph speed by
taking measurements
of time and distance.
•For instance: The
following
measurements were
taken on how fast a
turtle walks along a
path.
Time (h)Distance (m)
0 0
1 5
2 10
3 15
4 15
5 15
6 10
7 5

22. Speed (m/h)
0
5
10
15
20
1 2 3 4 5 6 7 8
Time (h)
D
i
s
t
a
n
c
e

(
m
)

23. Speed (m/s)
0
5
10
15
20
1 2 3 4 5 6 7 8
Time (s)
D
i
s
t
a
n
c
e

(
m
)
At position A, is the object moving away from or
towards the reference point?
At position C, is the object moving away from or
towards the reference point?
A
B
C

24. Steeper Slope = Faster Speed
0
2
4
6
8
10
12
14
1 2 3 4 5 6 7
Time (s)
D
i
s
t
a
n
c
e

(
m
)
Flatter Slope - Slower Speed
0
2
4
6
8
10
12
14
12345678910111213
Time (s)
D
i
s
t
a
n
c
e

(
m
)
Series2
The steeper the
slope, the faster
the speed.
The flatter the
slope, the slower
the speed.

25. Steeper Slope = Faster Speed
0
2
4
6
8
10
12
14
1 2 3 4 5 6 7
Time (s)
D
is
ta
n
c
e
(m
)
When the slope of the line is horizontal to the
x-axis, the speed is zero (the object is not
moving)

26. Examples:
•Lets graph the motion
of a drag racer.
Time (s)Distance (m)
0 0
5 20
10 40
15 60
20 80
30 100
40 120
Have to
allow for a
#25 and #35
on your X
axis!

27. First, we need to label the data x
and y.
Time (s) Distance (m)
0 0
5 20
10 40
15 60
20 80
30 100
40 120
X axis Y axis

28. Next, draw and label the graph.
Speed
0
20
40
60
80
100
120
140
1 2 3 4 5 6 7
Time (s)
D
i
s
t
a
n
c
e

(
m
)

29. Now, you need to plot the points.
Time
(s)
Distance
(m)
0 0
5 20
10 40
15 60
20 80
30 100
40 120

30. Practice Problem:
•Graph the speed of
an object as it travels
down hill.
Time (s)Distance
(m)
0 0
1 2
2 5
3 9
4 15
5 20
Time (s)Distance
(m)
0 0
1 10
2 8
3 5
4 3
5 1
Graph the speed of an object
as it travels up hill.