Using the Metric System A. Why do scientists use the metric system? The metric system was developed...
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Using the Metric System A. Why do scientists use the metric system? The metric system was developed in France in 1795 - used in all scientific work because it has been recognized as the world wide system of measurement since 1960. SI system is from the French for Le Systeme International d’Unites. The metric system is used in all scientific work because it is easy to use. The metric system is based upon multiples of ten. Conversions are made by simply moving the decimal point.
Using the Metric System A. Why do scientists use the metric system? The metric system was developed in France in 1795 - used in all scientific work because
Using the Metric System A. Why do scientists use the metric
system? The metric system was developed in France in 1795 - used in
all scientific work because it has been recognized as the world
wide system of measurement since 1960. SI system is from the French
for Le Systeme International dUnites. The metric system is used in
all scientific work because it is easy to use. The metric system is
based upon multiples of ten. Conversions are made by simply moving
the decimal point.
Slide 2
What is the basic unit of length? The meter a little longer
than a yard
Slide 3
What do scientists use to measure the length of an object
smaller than a yard? A centimeter one hundredth of a meter, so
there are 100 centimeters in a meter A millimeter There are 1,000
millimeters in a meter
Slide 4
How do scientists measure long distances? The kilometer There
are 1,000 meters in a kilometer
Slide 5
Which measurement to USE?
Slide 6
Base Units (Fundamental Units) QUANTITY NAME SYMBOL
_______________________________________________ Length meter m
-----------------------------------------------------------------------------
Mass gram g
-------------------------------------------------------------------------------
Time second s
-------------------------------------------------------------------------------
Temperature Kelvink
--------------------------------------------------------------------------------
Volume(liquid)__________liter_____________L________________
Slide 7
SI Prefixes Prefix Symbol Multiplication Factor Term Micro u
(0.000 001) one millionth Milli m (0.001) one thousandth Centi c
(0.01) one hundredth Deci d (0.1) one tenth One Unit 1 one Deka dk
10 ten Hecto h 100 one hundred Kilo k 1000 one thousand Mega M 1
000 000 one million
Slide 8
Metric Units Used In This Class QUANTITY NAME SYMBOL Length
meter m centimeter cm millimeter mm kilometer km Mass gram g
kilogram kg centigram cg milligram mg Volume liter (liquid) L (l)
milliliter (liquid) mL (ml) cubic centimeter (solid) cm3
Slide 9
Derived Units Base Units independent of other units-measure
Derived Units combination of base units-calculated Examples density
g/L mass / volume (grams per liter) volume m x m x m = meters cubed
Velocity m/s (meters per second
Slide 10
SCIENTIFIC NOTATION Scientific Notation: Easy way to express
very large or small numbers A.0 x 10 x A number with one non-zero
digit before decimal x -exponent- whole number that expresses the
number decimal places if x is (-) then it is a smaller if x is (+)
than it is larger
Slide 11
PRACTICE Convert to NormalConvert to SN 2.3 x 10 23 m3,400,000,
3.4 x 10 -5 cm.0000000456
Slide 12
Multiplying Calculating in Scientific notation Multiplying-
Multiple the numbers Add the exponents (2.0 x 10 4 ) (4.0 x 10 3 )
= 8.0 x 10 7
Slide 13
Dividing divide the numbers subtract the denominator exponent
from the numerator exponent 9.0 x 10 7 3.0 x 10 2 3.0 x 10 5
Slide 14
Add Add or subtract get the exponents of all # to be the same
calculate as stated make sure the final answer is in correct
scientific notation form 7.0 x 10 4 + 3.0 x 10 3 = 7. 0 x 10 4 +.3
x 10 4 = 7.3 x 10 4 70,000 + 3,000 = 73000= 7.3 x10 4
Slide 15
subtract 7.0 x 10 4 - 3.0 x 10 3 = 7.0x 10 4 .30 x 10 4 = 6.7 x
10 4 70,000 - 3 000 =67,000
Slide 16
PRACTICE Add: 2.3 x 10 3 cm + 3.4 x 10 5 cm Subtract: 2.3 x 10
3 cm - 3.4 x 10 5 cm Multiply: : 2.3 x 10 3 cm X 3.4 x 10 5 cm
Divide: : 2.3 x 10 3 cm / 3.4 x 10 5 cm
value determined by the instrument of measurement plus one
estimated digit reflects the precision of an instrument example if
an instrument gives a length value to the tenth place you would
estimate the value to the hundredths place Using Significant
Figures (Digits)
Slide 19
Mathematical Operations Involving Significant Figures
Multiplication and Division The answer must have the same number of
significant figures as the measurement with the fewest significant
figures.
Slide 20
Making Unit Conversions Make conversions by moving the decimal
point to the left or the right using: king henry died unit drinking
chocolate milk Examples 1. 10.0 cm = __________m 2. 34.5 mL =
__________L 3. 28.7 mg = __________kg
Slide 21
Factor label method / Dimensional analysis Use equalities to
problem solve converting units. quantity desired = quantity given x
conversion factor (equality) A-given unit B-desired unit C-given
unit A x B C B C must equal 1 use equality sheet
Slide 22
Equalities You Need To Know 1 km = 1000 m 1 m = 100 cm 1 m =
1000 mm 1L = 1000 mL 1kg = 1000g 1 g = 100cg 1 g = 1000 mg
Slide 23
ENGLISH TO METRIC 1 inch=2.5 centimeters 1 gal=3.8 liters 1lb=
4.4 Newtons 1qt =.94 Liters 1 ft =.30 meters 12 in =.30 meters 1 mi
= 1.6 Km
Slide 24
Four-step approach When using the Factor-Label Method it is
helpful to follow a four-step approach in solving problems: 1.What
is question How many sec in 56 min 2. What are the equalities- 1
min = 60 sec 3. Set up problem (bridges) 56 min 60 sec 1 min 4.
Solve the math problem -multiple everything on top and bottom then
divide 56 x 60 / 1
Slide 25
Motion Describing and Measuring Motion How do you recognize
motion? An object is in motion when its distance from another
object is changing Movement depends on your point of view
Slide 26
Distance We all know what the distance between two objects
is... So what is it? What is distance? What is length? ALSO - you
can't use the words "distance" or "length" in your definition; that
would be cheating.
Slide 27
Distance As you can see from your efforts, it is impossible to
define distance. Distance is a fundamental part of nature. It is so
fundamental that it's impossible to define. Everyone knows what
distance is, but no one can really say what it is. However,
distances can be compared.
Slide 28
Distance We can compare the distance between two objects to the
distance between two other objects. For convenience, we create
standard distances so that we can easily make comparisons... and
tell someone else about them. This doesn't define distance, but it
allows us to work with it.
Slide 29
Distance We'll be using meter as our standard for measuring
distance. The symbol for distance is "d". And the unit for the
meter is "m. d = 0.2 m
Slide 30
Distance Activity 1. Work in partners create a difference in
position between you and a partner. Use a meter stick to determine
the distance between you and your partner.( position A) 2. Now move
to a different position. Measure the difference in your position
now. ( Position B) make note of the distance you have
traveled?
Slide 31
Time Similarly, everyone knows what time is... But try defining
it; what is time? Remember you can't use the word "time" or an
equivalent to the word "time", in your definition.
Slide 32
Time Like distance, time is a fundamental aspect of nature. It
is so fundamental that it's impossible to define. Everyone knows
what time is, but no one can really say what it is... However, like
distances, times can be compared.
Slide 33
Time We can say that in the time it took to run around the
track, the second hand of my watch went around once...so my run
took 60 seconds. When we compare the time between two events to the
time between two other events, we are measuring time. This doesn't
define time, but it allows us to work with it.
Slide 34
Time We will be using the second as our standard for measuring
time. The symbol for time is "t" The unit for a second is "s". t =
10s click here for a "minute physics" on measuring time and
distance
Slide 35
Time Activity Repeat previous distance activity Use a timer use
seconds as the unit 1. Determine the time it took to go from
position A to position B Draw a diagram of your activity List the
known information- Distance: between position A to position B Time:
it took to go from A to B
Slide 36
How do scientists calculate speed? Speed the distance the
object travels in one unit of time Rate tells you the amount of
something that occurs or changes in one unit of time Speed =
distance time
Slide 37
Speed s = d t meters second m s The units of speed can be seen
by substituting the units for distance and time into the equation
We read this unit as "meters per second"
Slide 38
SPEED = Distance / time Use the information from the previous
two activities to calculate your speed. Use these steps 1. draw a
diagram 2. list known and unknown data 3. write the formula you
will use 4. plug in data 5. solve the problem using the correct
units
Slide 39
1 A car travels at a constant speed of 10m/s. This means the
car: A increases its speed by 10m every second. B decreases its
speed by 10m every second. Cmoves with an acceleration of 10 meters
every second. Dmoves 10 meters every second. c c c c
Slide 40
2 A rabbit runs a distance of 60 meters in 20 s; what is the
speed of the rabbit?
Slide 41
How can you calculate the distance an object has moved?
Rearrange the speed formula Speed = distance/time Distance = Speed
x Time
Slide 42
Rearrange the following formula Speed =distance time
Find-distance: what you do to one side you do to the other time x
speed = distance x time time distance=time x speed Find- time: what
you do to one side you do to the other distance= time x speed speed
speed Time =distance speed
Slide 43
3 A car travels at a speed of 40 m/s for 4.0 s; what is the
distance traveled by the car?
Slide 44
4 You travel at a speed of 20m/s for 6.0s; what distance have
you moved?
Slide 45
5 An airplane on a runway can cover 500 m in 10 s; what is the
airplane's average speed?
Slide 46
Solve for time:
Slide 47
6 You travel at a constant speed of 20 m/s; how much time does
it take you to travel a distance of 120m?
Slide 48
7 You travel at a constant speed of 30m/s; how much time does
it take you to travel a distance of 150m?
Slide 49
Graphing graph a visual representation of data that reveals a
pattern Bar- comparison of different items that vary by one factor
Circle depicts parts of a whole Line graph- depicts the
intersection of data for 2 variables Independent variable- factor
you change Dependent variable the factor that is changed when
independent variable changes
Slide 50
Graphing Creating a graph- must have the following points 1.
Title graph 2. Independent variable on the X axis horizontal-
abscissa 3. Dependent variable on Y axis vertical- ordinate 4. Must
label the axis and use units 5. Plot points 6. Scale use the whole
graph 7. Draw a best fit line- do not necessarily connect the dots
and it could be a curved line.
Slide 51
Interpreting a graph Slope- rise Y2 Y1 Run X2 X1 relationship
direct a positive slope inverse- a negative slope equation for a
line y = mx + b m-slope b y intercept extrapolate-points outside
the measured values- dotted line interpolate- points not plotted
within the measured values-dotted line
Slide 52
WORK ON GRAPHING EXERCISES Graphical analysis click and go
Slide 53
What is average speed? Most objects do not move at constant
speeds for very long To find average speed divide the total
distance by the total time Car trip
Slide 54
How do you graph motion? You can show the motion of an object
on a line graph in which you plot distance against time Time is
along the x- axis independent variable and distance on the y-axis
dependent variable
Slide 55
How do you interpret motion graphs? A straight line indicates a
constant speed The steepness depends on how quickly or slowly the
object is moving The faster the motion the steeper the slope
Slide 56
Bulldozer Lab
Slide 57
Return to Table of Contents Average Speed
Slide 58
The speed we have been calculating is a constant speed over a
short period of time. Another name for this is instantaneous speed.
If a trip has multiple parts, each part must be treated separately.
In this case, we can calculate the average speed for a total trip.
Determine the average speed by finding the total distance you
traveled and dividing that by the total time it took you to travel
that distance.
Slide 59
In physics we use subscripts in order to avoid any confusion
with different distances and time intervals. For example: if an
object makes a multiple trip that has three parts we present them
as d 1, d 2, d 3 and the corresponding time intervals t 1, t 2, t
3. Distance and Time Intervals
Slide 60
The following pattern of steps will help us to find the average
speed: Find the total distance d total = d 1 + d 2 + d 3 Find the
total time t total = t 1 + t 2 + t 3 Use the average speed formula
Average Speed & Non-Uniform Motion s avg = d total t total
Slide 61
Average Speed - Example 1 You ride your bike home from school
by way of your friends house. It takes you 7 minutes (420 s) to
travel the 2500 m to his house. You spend 10 minutes there, before
traveling 3500 m to your house in 9 minutes (540 s). What was your
average speed for this trip? To keep things clear, we can use a
table to keep track of the information...
Slide 62
Example 1 - Step 1 You ride your bike home from school by way
of your friends house. It takes you 7 minutes (420 s) to travel the
2500 m to his house. You spend 10 minutes there, before traveling
3500 m to your house in 9 minutes (540 s). What was your average
speed for this trip? SegmentDistanceTimeSpeed (m)(s)(m/s) I II III
Total /Avg. Write the given information in the table below:
Slide 63
Example 1 - Step 2 You ride your bike home from school by way
of your friends house. It takes you 7 minutes (420 s) to travel the
2500 m to his house. You spend 10 minutes there, before traveling
3500 m to your house in 9 minutes (540 s). What was your average
speed for this trip? SegmentDistanceTimeSpeed (m)(s)(m/s) I
2500m420 s II 0 m600 s III 3500m540 s Total /Avg. Next, use the
given information to find the total distance and total time
Slide 64
Example 1 - Step 2 You ride your bike home from school by way
of your friends house. It takes you 7 minutes (420 s) to travel the
2500 m to his house. You spend 10 minutes there, before traveling
3500 m to your house in 9 minutes (540 s). What was your average
speed for this trip? SegmentDistanceTimeSpeed (m)(s)(m/s) I
2500m420 s II 0 m600 s III 3500m540 s Total /Avg. 6000m1560s Next,
use the given information to find the total distance and total
time
Slide 65
Example 1 - Step 3 You ride your bike home from school by way
of your friends house. It takes you 7 minutes (420 s) to travel the
2500 m to his house. You spend 10 minutes there, before traveling
3500 m to your house in 9 minutes (540 s). What was your average
speed for this trip? SegmentDistanceTimeSpeed (m)(s)(m/s) I
2500m420 s II 0 m600 s III 3500m540 s Total /Avg. 6000m1560s Next
use total distance and time to find average speed.
Slide 66
Example 1 - Solution You ride your bike home from school by way
of your friends house. It takes you 7 minutes (420 s) to travel the
2500 m to his house. You spend 10 minutes there, before traveling
3500 m to your house in 9 minutes (540 s). What was your average
speed for this trip? SegmentDistanceTimeSpeed (m)(s)(m/s) I
2500m420 s II 0 m600 s III 3500m540 s Total /Avg. 6000m1560s3.85
m/s Next use total distance and time to find average speed.
Slide 67
Example 2 SegmentDistanceTimeSpeed (m)(s)(m/s) I II III Total
/Avg. You run a distance of 210 m at a speed of 7 m/s. You then jog
a distance of 200 m in a time of 40s. Finally, you run for 25s at a
speed of 6 m/s. What was the average speed of your total run?
Slide 68
Example 2 - Reflection SegmentDistanceTimeSpeed (m)(s)(m/s) I
210307 m/s II 200405 m/s III 150256 m/s Total /Avg. 560955.89 m/s
What happens when you take the 'average' (arithmetic mean) of the
speed for each leg of the trip? Is it the same as the average
speed? Why do you think this happens?
Slide 69
Return to Table of Contents Position and Reference Frames
Slide 70
Speed, distance and time didn't require us to define where we
started and where we ended up. They just measure how far we
traveled and how long it took to travel that far. However, much of
physics is about knowing where something is and how its position
changes with time. To define position we have to use a reference
frame.
Slide 71
Position and Reference Frames A reference frame lets us define
where an object is located, relative to other objects. For
instance, we can use a map to compare the location of different
cities, or a globe to compare the location of different continents.
However, not every reference frame is appropriate for every
problem.
Slide 72
Reference Frame Activity Send a volunteer out of the classroom
to wait for further instructions. Place an object somewhere in your
classroom. Write specific directions for someone to be able to
locate the object Write them in a way that allows you to hand them
to someone who can then follow them to the object. Test your
directions out on your classmate, (who is hopefully still in the
hallway!) Remember: you can't tell them the name of something your
object is near, just how they have to move to get to it. For
instance 'walk to the SmartBoard' is not a specific direction.
Slide 73
Reference Frame Activity - Reflection In your groups, make a
list of the things you needed to include in your directions in
order to successfully locate the object in the room. As a class,
discuss your findings.
Slide 74
You probably found that you needed: A starting point (an
origin) A set of directions (for instance left-right,
forward-backward, up-down) A unit of measure (to dictate how far to
go in each direction) Results - Reference Frames
Slide 75
In this course, we'll usually: Define the origin as a location
labeled "zero" Create three perpendicular axes : x, y and z for
direction Use the meter as our unit of measure Results - Reference
Frames
Slide 76
In this course, we will be solving problems in one-dimension.
Typically, we use the x-axis for that direction. +x will usually be
to the right -x would then be to the left We could define it the
opposite way, but unless specified otherwise, this is what we'll
assume. We also can think about compass directions in terms of
positive and negative. For example, North would be positive and
South negative. The symbol for position is "x". The Axis +x- x
Slide 77
8 All of the following are examples of positive direction
except: Ato the right B north Cwest Dup
Slide 78
Return to Table of Contents Displacement
Slide 79
Now that we understand how to define position, we can talk
about a change in position; a displacement. The symbol for "change"
is the Greek letter "delta" "". So "x" means the change in x or the
change in position
Slide 80
-x +y -y +x Displacement Displacement describes how far you are
from where you started, regardless of how you got there.
Slide 81
-x +y -y +x Displacement For instance, if you drive 60 miles
from Pennsylvania to New Jersey... x0x0 (In physics, we label the
starting position x 0 )
Slide 82
-x +y -y +x Displacement and then 20 miles back toward
Pennsylvania. x0x0 xfxf (We also label the final position x f
)
Slide 83
-x +y -y +x Displacement You have traveled: a distance of 80
miles, and a displacement of 40 miles, since that is how far you
are from where you started x0x0 xfxf we can calculate displacement
with the following formula: x = X f - X o
Slide 84
Displacement Measurements of distance can only be positive
values (magnitudes) since it is impossible to travel a negative
distance. Imagine trying to measure a negative length with a meter
stick...
Slide 85
xfxf xoxo -x +y -y +xxoxo xfxf -x +y -y +x Displacement
However, displacement can be positive or negative since you can end
up to the right or left of where you started. Displacement is
positive.Displacement is negative.
Slide 86
Vectors and Scalars Scalar - a quantity that has only a
magnitude (number or value) Vector - a quantity that has both a
magnitude and a direction QuantityVectorScalar Time Distance
Displacement Speed Which of the following are vectors?
Scalars?
Slide 87
9 How far your ending point is from your starting point is
known as: Adistance Bdisplacement Ca positive integer Da negative
integer
Slide 88
10 A car travels 60m to the right and then 30m to the left.
What distance has the car traveled? +x- x
Slide 89
11 You travel 60m to the right and then 30m to the left. What
is the magnitude (and direction) of your displacement? +x- x
Slide 90
12 Starting from the origin, a car travels 4km east and then 7
km west. What is the total distance traveled? A3 km B-3 km C7 km
D11 km
Slide 91
13 Starting from the origin, a car travels 4km east and then 7
km west. What is the net displacement from the original point? A 3
km west B3 km east C 7 km west D11 km east
Slide 92
14 You run around a 400m track. At the end of your run, what is
the distance that you traveled?
Slide 93
15 You run around a 400m track. At the end of your run, what is
the displacement you traveled?
Slide 94
16Which of the following is a vector quantity? Atime B velocity
C distance Dspeed c c
Slide 95
Return to Table of Contents Average Velocity
Slide 96
What is Velocity? Speed in a given direction When you know the
speed and direction of an objects motion, you know the velocity of
the object Example 15 km/hour westward
Slide 97
Average Velocity Speed is defined as the ratio of distance and
time Similarly, velocity is defined as the ratio of displacement
and time s = d t xx tt v = Average velocity = time elapsed
displacement Average speed = distance traveled time elapsed
Slide 98
Average Velocity Speeds are always positive, since speed is the
ratio of distance and time; both of which are always positive. But
velocity can be positive or negative, since velocity is the ratio
of displacement and time; and displacement can be negative or
positive. s = d t xx tt v = Usually, right is positive and left is
negative. Average speed = distance traveled time elapsed Average
velocity = time elapsed displacement
Slide 99
17 Average velocity is defined as change in ______ over a
period of ______. Adistance, time Bdistance, space Cdisplacement,
time Ddisplacement, space c c c c
Slide 100
18 Velocity is a vector. True False c c
Slide 101
19 You travel 60 meters to the right in 20 s; what is your
average velocity?
Slide 102
20 You travel 60 meters to the left in 20 s; what is your
average velocity?
Slide 103
21 You travel 60 meters to the left in 20 s and then you travel
60 meters to the right in 30 s; what is your average velocity?
Slide 104
22 You travel 60 meters to the left in 20 s and then you travel
60 meters to the right in 30 s; what is your average speed?
Slide 105
25 You travel 160 meters in 60 s; what is your average
speed?
Slide 106
DOT DIAGRAM GO TO PHYSICS CLASSROOM TO PRACTICE DOT DIAGRAM
EXAMPLES. Ticker Tape Diagrams- dot diagram The distance between
dots on a ticker tape represents the object's position change
during that time interval. A large distance between dots indicates
that the object was moving fast during that time interval. A small
distance between dots means the object was moving slow during that
time interval. Ticker tapes for a fast- and slow-moving object are
depicted below.
Slide 107
Dot diagram-
Slide 108
Slide 109
Return to Table of Contents Instantaneous Velocity
Slide 110
Sometimes the average velocity is all we need to know about an
object's motion. For example: A race along a straight line is
really a competition to see whose average velocity is the greatest.
The prize goes to the competitor who can cover the displacement in
the shortest time interval. But the average velocity of a moving
object can't tell us how fast the object moves at any given point
during the interval t.
Slide 111
Instantaneous Velocity Average velocity is defined as change in
position over time. This tells us the 'average' velocity for a
given length or span of time. Watch what happens when we look for
the instantaneous velocity by reducing the amount of time we take
to measure displacement. Instantaneous Velocity- velocity of an
object at a specific point in time If we want to know the speed or
velocity of an object at a specific point in time (with this radar
gun for example), we want to know the instantaneous
velocity...
Slide 112
Instantaneous Velocity DisplacementTime 100m10 s Velocity In an
experiment, an object travels at a constant velocity. Find the
magnitude of the velocity using the data above.
Slide 113
Instantaneous Velocity What happens if we measure the distance
traveled in the same experiment for only one second? What is the
velocity? 10 m 1 s DisplacementTimeVelocity 100m10 s10 m/s
Slide 114
Instantaneous Velocity What happens if we measure the distance
traveled in the same experiment for a really small time interval?
What is the velocity? 10 m 1 s10 m/s 0.001m0.0001 s
DisplacementTimeVelocity 100m10 s10 m/s
Slide 115
DisplacementTimeVelocity 100 m10 s10 m/s 10 m1 s10 m/s 1.0
m0.10 s10 m/s 0.10 m0.010 s10 m/s 0.010 m0.0010 s10 m/s 0.0010
m0.00010 s10 m/s 0.00010 m0.000010 s10 m/s Instantaneous Velocity
Since we need time to measure velocity, we can't know the exact
velocity "at" a particular time... but if we imagine a really small
value of time and the distance traveled, we can estimate the
instantaneous velocity.
Slide 116
To describe the motion in greater detail, we need to define the
velocity at any specific instant of time or specific point along
the path. Such a velocity is called instantaneous velocity. Note
that the word instant has somewhat different meaning in physics
than in everyday language. Instant is not necessarily something
that is finished quickly. We may use the phrase "It lasted just an
instant" to refer to something that lasted for a very short time
interval. Instantaneous Velocity
Slide 117
In physics an instant has no duration at all; it refers to a
single value of time. One of the most common examples we can use to
understand instantaneous velocity is driving a car and taking a
quick look on the speedometer. Instantaneous Velocity At this
point, we see the instantaneous value of the velocity.
Slide 118
Instantaneous Velocity The instantaneous velocity is the same
as the magnitude of the average velocity as the time interval
becomes very very short. xx t as t 0 close to zero v =
Slide 119
Instantaneous Velocity (a) When the velocity of a moving object
is a constant the instantaneous velocity is the same as the
average. v (m/s) t (s) v (m/s) t (s) These graphs show (a) constant
velocity and (b) varying velocity. (b) When the velocity of a
moving object changes its instantaneous velocity is different from
the average velocity.
Positive Velocity Positive Velocity Changing Velocity
(acceleration) Constant velocity to Speeding up
Slide 122
Slow, Leftward(-) Constant Velocity Fast, Leftward(-) Constant
Velocity Slowing down
Slide 123
Velocity time graphs CONSTANT VELOCITY Calculate distance using
v=d/t for 3 and 5 secs
Slide 124
Position time graph Constant Velocity Calculate velocity using
v=d/t for 3 and 5 secs
Slide 125
Constant Positive Velocity Observe that the object below moves
with a constant velocity in the positive direction. The dot diagram
shows that each consecutive dot is the same distance apart (i.e., a
constant velocity). The position-time graph shows that the slope is
both constant (meaning a constant velocity) and positive (meaning a
positive velocity). The velocity-time graph shows a horizontal line
with zero slope (meaning that there is zero acceleration); the line
is located in the positive region of the graph (corresponding to a
positive velocity). The acceleration-time graph shows a horizontal
line at the zero mark (meaning zero acceleration).
http://www.physicsclassroom.com/mmedia/kinem a/cpv.gif
Slide 126
v (m/s) t (s) The graph below shows velocity versus time. How
do you know the velocity is constant? Velocity Graphing
Activity
Slide 127
v (m/s) t (s) The graph below shows velocity versus time. When
is the velocity increasing? Decreasing? Constant? Velocity Graphing
Activity