INTRODUCTORY PHYSICS REMOTE LAB REPORT ON UNIFORM MOTION
STUDENT NAME: Sean Saenz
Objective:
In this experiment, we will learn about describing the motion of objects moving with uniform
motion.
Theory: We are going to use a video experiment to describe the position and displacement of a cart moving
with a uniform motion.
Position describes the location of a point with respect to some origin.
The displacement of an object is the distance between two points along with the direction from one point to
another.
We will be investigating “ticker-tape” diagrams. In these diagrams, a ticker-tape machine makes a dot on a
strip of paper after a certain interval (i.e., every 1/10th of second).
The strip of paper is attached to an object that moves away from the machine.
The tape records the position of the object after each interval.
Below inserted URL is just to show you how the equipment looks like and how it can track the uniform
motion of a toy cart. The actual sequence of marked dots that you will work with is on the next page, in
diagram format, with a ruler overlapping onto its 7 total marked positions as a function of the time of the
motion. The entire tracking of the motion lasts just 0.7 seconds.
Equipment:
video: https://youtu.be/NX20xE-C1sg
Uniform Motion
Type Your Full Name: Sean Saenz
EXPERIMENT:
In this experiment, a motorized car is attached to a strip of paper. Start by viewing the video of the
experiment: Buggy Video
Buggy Video inserted URL is just to show you how the equipment looks like and how it can track the
uniform motion of a toy cart. The actual sequence of marked dots that you will work with is on the next
page, in diagram format, with a ruler overlapping onto its 7 total marked positions as a function of the time
of the motion. The entire tracking of the motion lasts just 0.7 seconds. The Ticker Tape Timer that puts a
little dot on the paper each 1/10th of a second (or 0.1 s) that the buggy moves. The origin will be the first dot
that we can see on the paper. The displacement for each 0.1s will be determined by looking at the distance
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(on the meterstick) between each dot. Use ONLY the metric system and the ruler’s side with cm marks.
Remember to convert from centimeters (cm) into meters (m), when required.
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DATA: The following is a sample of the data from the experiment:
QUESTION 1: Before going any further, look at the dots on the strip that occur after the first dot.
How would you describe the positions of these dots?
Are the dots getting closer together, further apart or are they equally spaced?
I would describe the dots as equally space with minor excess space in between.
1. Record the position of the second dot on the ruler using centimeters (if you are using word, there is a
little red line that you can move to measure accurately). Be careful to measure at least to the mm.
Record this in the Table for time 0.1s.
Repeat this for each of the dots that you have available adding 0.1s for each consecutive dot and record
this information in the Table.
2. Calculate the displacement between each of the dots (position of second dot – position of previous) and
record it in the Table.
Be careful to calculate the displacement between each dot and not between each dot and the origin.
QUESTION 2: How do the displacements in the table compare?
Are they getting bigger, smaller or staying the same?
After calculating the displacements in between each dot, I found there is a 0.1 difference from the 0 second
to the 0.1 second as well as a 0.1 difference between the 0.4 second and the 0.5 second. In comparison, the
rest of the displacement values for the other times and positions are the same.
Explain how uncertainty in measurement plays a role in answering this question.
Uncertainty in measurement plays a role in answering this question by different individuals can determine
the point as a different value than another individual. Moreover, the units that an individual is measuring in
can cause uncertainty as well.
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How does your answer to this question support (or not), your answer to Question 1?
This supports my answer to Question 1 because viewing the data tables and the displacements in between
each 1/10th of a second there is little difference in between the position and displacement of each time.
Note: there is no mistake in sliding the third column on the data table below. Displacement represents the
difference in between the final and the initial position of the moving buggy. Calculate each of the
displacement values out of the data measured with the ruler by the paper strip of the experiment.
DATA TABLE
Time (s)
Position (cm)
Displacement (xf-xi)
0
0.0
2.1
0.1
2.1
2.2
0.2
4.3
2.2
0.3
6.5
2.2
0.4
8.7
2.1
0.5
10.8
2.2
0.6
13
2.2
0.7
15.2
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3. Make a graph of position versus time. (First, learn from the “All About Graphs” Section on the
following pages)
QUESTION 3: What does your graph of Position (in cm) versus Time (in s) look like?
Does the data appear to be a straight line or is there some curve to the data?
The data in the graph shows that it is a straight line.
How does this support (or Not) how you answered Questions 1 and 2?
This supports how I answered in the Questions 1 and 2 because the points are positions are equally spaced
out causing a slope and the displacements show that the equal change in the position of the point.
4. Your graph should show a straight-line relationship between Position and Time.
Use any method to draw a “best fit” line to the data. (This is a line that BEST represents your
measured data. The line may not intersect any of your data points, but best get the closest to the most
of them, minimizing the distance between this best fit line and each of the measured and plotted
values of your measured data).
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Find the slope of this straight-line graph by choosing any two dots on the best fit line and using
𝑥2 −𝑥1
4.3𝑐𝑚−2.1𝑐𝑚 2.2𝑐𝑚
the equation:
𝑡2 −𝑡1
0.2𝑠−0.1𝑠
0.1𝑠
𝑠𝑙𝑜𝑝𝑒 =
=
=
= 22cm/s
where the two chosen points have their coordinates represented by the algebraic, symbolic
representations of the above generic formula.
QUESTION 4: What is the physical meaning of the slope of this graph of position versus time?
(What does it describe about the motion of the car?)
specifically at the beginning of chapter 2.
Hint: we learned about it in the textbook material,
What the meaning of the motion of the car is that it is travelling is unchanged which is making the
velocity constant. Furthermore, that means the slope of the position-time graph is equal to the speed of
the car.
What would be different about the motion of this car if the slope of this graph were steeper?
The difference about the motion of this car if the slope of this graph were steeper would be that the speed
would be increasing or faster.
What would be different if it were less steep?
If the slope was less steep or flatter (more horizontal) then the speed of the car would be described as
slower.
QUESTION 5: If the car could move (with exactly the very same motion characteristics as the ones
from the given measured sets of data from page 2 and tabulated by you on page 3)
for a total time of 2.0 s instead of just 1.0s, then calculate how far (from the very same starting point)
the car would move?
D= speed x change in time = 22 cm/s x 2.0s = 44 cm
Using the same graph as I used for Question 3 and calculating further using the same displacement and
assuming the car is moving the same speed as well as the same starting point, I determined that the car
would move approximately 44 centimeters in total over the course of 2.0s to prove that the speed is
constant.
How long (in seconds of time of travel) would it take for the car to move a total distance across
a 2.00 m (notice that this is meters) table? Here you need to convert your already calculated constant
speed from cm/s into m/s. Remember that it takes 100cm to make up 1m of length.
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2.00 m = 200 cm; time=
𝑑𝑖𝑠𝑡𝑎𝑛𝑐𝑒
𝑠𝑝𝑒𝑒𝑑
2.00 𝑚
; time= 0.216 𝑚/𝑠= 9.25926 seconds
ALL ABOUT GRAPHS
Graphs are an essential part of understanding physical phenomena. In this course, we will be
constructing and interpreting graphs frequently. You may use a computer program to make your
graphs or you may make your graphs by hand. In either case, there are some things that you should
know. This is a quick tutorial about how to make graphs.
ABOUT THE AXES
parkers (cars)
The graph always has two axes, on for the y-variable (ordinate axis) and one for the x-variable (the
abscissa). You should always mark your axes with the variable that you are plotting and the units that
the variable is measured in. This will help others who are trying to read the graphs and will be helpful
to you when you are referring back to a graph. Usually, you will be told which variable to plot on which
axis. If you are not, the rule is that the independent variable is plotted on the x-axis and the dependent
variable is on the y-axis. The independent variable is exactly how it sounds; it is the variable that you
manipulate. The dependent variable is the one that you measure that is
dependent on the independent variable. For example, say we were doing
an experiment to find out how the number of cars parked in the parking lot
changes over time. We would choose certain times to measure, say the 10
minutes past every hour from 8AM until 5PM. Time is the independent
variable since we are choosing when we are going to measure. It goes on
the x-axis. We will count the number of cars parked in the lot at each of
these times. The number of cars is the dependent variable. In theory, the
number of cars depends on the time of day. It is also the variable that we
time of day (hours)
choose to measure and we don’t know at the outset what its value is going
to be. My graph might look like the graph on the right.
USING THE GRAPH PAPER: If you are making the graph by hand or using the graph paper attached,
your first question may be about what the scale of your graph should be. You should include 0 on your
graph unless it is not appropriate (as in our example above since we start counting cars at 8AM). It is
your call whether 0 should be on the graph or not. The other rule is to use as much of the graph paper
as possible. Try not to squish the entire graph into one corner. Look at the range of data points that
you have the number of intervals on your graph paper. Divide the two numbers and find an interval
value that makes sense for your graph and contains all of your data points. For example, say your data
points go from 1s to 7.7s and you have 11 intervals on your graph paper. To include all of your data
points (and zero), the smallest value of each square is 0.7s. That might be okay for your computer
program to use, but you should probably round the interval up to 1.0s in order to make the intervals
easy for you to graph.
USING A COMPUTER PROGRAM:
If you have Excel on your computer, you can put your data into the two columns in the program.
The first column should be the x-axis data.
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The second column should be the y-axis data.
You should label the data columns appropriately.
When you have entered the data, you should highlight the columns (include the data labels) and go to
the “Insert” ribbon.
Choose a scatterplot graph.
When your graph is complete, you can select the graph and copy it and then Paste it into your lab
report.
Another program that is easy is to use is Demos (https://www.desmos.com). This is an online
program which only makes graphs. Use the + sign in the upper left side to choose a Table to make a
graph.
To get this graph into your lab report, take a screen shot of the graph and paste it into your
report.
FINDING THE SLOPE OF A LINE
𝑦 = 𝑚𝑥 + 𝑏,
When the relationship for variables is linear, it follows the equation:
where m is
the slope of the line and b is the y intercept. The y-intercept is the value of y when x is equal to zero.
The slope describes the numerical relationship between the variables and is computer using the rise
divided by the run of the line. To find the slope, first you have to draw a best fit line. In drawing the
line, you don’t have to connect your data points.
In fact, you should NEVER CONNECT YOUR DATA POINTS. The line should best represent the trend
that your data is taking. The line may go through some or most of your points or it may not go through
any. If you are doing this by hand, use a ruler and draw the line. If you have the graph in a program,
use the drawing function to draw a line through your data. If you are using a graphing program, you
probably should NOT have the program draw a line a for you unless your data is perfectly linear.
Once you have drawn the best fit line, choose two points on the line that are relatively far away from
each other. Use points that make sense for your graph and are easy to find the components of.
Choosing the origin as one of your data points is often prudent if your line goes directly through.
DO NOT CHOOSE YOUR DATA POINTS. Circle the wo points that you are using. Find the components
𝑦2 −𝑦1
of the two points and calculate the slope using the following equation:
. Show your
𝑥2 −𝑥1
calculation on the graph itself and include your units.
𝑚=
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Analysis of the Measured Data and Conclusions
The data that was gathered was aimed at the objective to learn about uniform motion and its effect
on the motion of objects. The goal of the experiment was for us to view objects in motion with uniform
motion with the ticker-tape and toy car. After viewing the video link that was presented at the beginning
of the lab, it showed the ticker-tape machine car that was fed a piece of paper and dotted the piece of
paper for a specific interval as the toy car moved forward. When looking at the visual representation of
the ticker-tape machine ruler presented, I observed that the dots were placed equally apart from each
other. According to the meter stick visual that was provided, I needed to inspect where the ticker-tape
machine dotted on the ruler in the measurement of centimeters. After gathering the data and calculating
the displacements between each 1/10th of a second, I found that the dots were equally spaced apart with a
little error in terms of the displacement. This confirms that the speed of the ticker-tape machine was
constant. I then placed the data in to a graph and determined the slope was 22 cm/s. Looking at the graph,
the slope of the car was a positive slope, which also equals to velocity of the ticker-tape machine.
Comparing the graph to my measurement for the slope the values were approximately the same. In terms
of the sources of error for this experiment, there could be errors with the properties of the vehicle that
could play in to the speed of the car itself such as, the friction of the car rolling over the table or even the
way that the car was released that provided us with our data. At the end of the experiment, I determined
that the dots that were marked by the ticker-tape machine being pulled by the toy car were placed equally
apart. The positive slope of the graph concludes that the object was in constant speed whilst placing the
dots equally apart. The data shown confirmed my initial observation that the dots were placed equally
apart thus accomplishing the objective of describing the motion of objects moving with uniform motion.
In conclusion, the experiment and data gathered prove that the toy car with the ticker-tape machine were
moving in constant speed, the positive slope of the graph confirm this.
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