Plan an investigation to explore Newton’s first two laws of motion.
Time Approximately 60 minutes
Question How can Newton’s laws be experimentally verified?
Hypotheses Write each hypothesis you developed during the laboratory lesson.
Part I, Newton’s first law:
Part II, Newton’s second law:
Summary You will plan an investigation that demonstrates and validates Newton’s first two laws of
motion. Two experiments will be developed, one to focus on each law. You will be given
a toy car and sections of track to carry out the experiments.
Safety
Always wear safety goggles when performing an experiment.
Behavior in the lab needs to be purposeful. Use caution when manipulating objects and measuring their
motion.
Report all accidents—no matter how big or small—to your teacher.
Set up your experiment in an area that has enough room to take measurements, but is not so large as
to interfere with other people in the area.
Introduction
It is time to get you thinking about Newton’s first and second laws, and how you can demonstrate and
verify them. There are two parts to this lab. You will be given an example scenario for each, which will
help you think about the possible experiments you can build.
The first experiment you will devise should demonstrate Newton’s first law, also called the law of inertia,
which says an object in motion tends to stay in motion and an object at rest tends to stay at rest, unless
the object is acted upon by a force sufficient to change its motion. In what ways can this be
demonstrated?
The second experiment involves verifying Newton’s second law, which can be summarized as F = ma. In
other words, force is equal to mass times acceleration. To verify this, you will devise an experiment that
manipulates these three variables to determine the affect they have on each other.
Your teacher will let you know what materials are available, and you and your lab partners will plan your
investigations around this.
Student Guide (continued)
Example Scenarios
Part I: Demonstrating Newton’s First Law of Motion
Let’s start with an example of Newton’s first law, also called the law of inertia. The law of inertia applies to
resting or moving objects: an object in motion tends to stay in motion and an object at rest tends to stay at
rest, unless the object is acted upon by a force sufficient to change its motion.
Imagine you are going on a family trip, and your parents ask you to load the luggage onto the car’s roof
rack. The luggage sits on the porch, and has inertia: it will not move until you apply enough force to move
it. You decide to overcome the inertia of the luggage and load the car.
Now you are off on your trip. As the car speeds down the road toward your destination, your dad asks you
why there are luggage straps still in the back seat. Just as you realize why, a dog runs across the road
and your dad slams on the brakes. The dog manages to escape, but the luggage flies forward off the roof
rack, landing far ahead of the car on the road. You again recall the law of inertia: an object in motion (like
luggage on a speeding car) will stay in motion unless acted upon by a sufficient force (provided by
luggage straps). As your dad fumes, you explain Newton’s first law to him to divert his attention.
Part II: Verifying Newton’s Second Law of Motion
Your friend invites you out for a night of bowling. She is a very good bowler, and even has her own ball
and shoes. You have never bowled before but you think it looks pretty simple. Besides that, you have
recently been studying Newton’s laws and think you have a pretty good handle on how to be successful
at this game.
Your first strategy is to choose the heaviest ball available at the alley. Because you understand that F =
ma, you know that using a massive ball will impart a large force on the pins and you are sure to get a
strike! But when you attempt to roll the ball down the lane, it is so heavy that you have a hard time getting
it moving—or providing that other component of force, acceleration. Your choice of the massive ball
results in it traveling very slowly down the lane and while you do hit some pins, the ball sort of pushes
them out of the way rather than blasting them apart. Your friend looks on and smirks.
New strategy: since the massive ball is too heavy to move, choose a very light ball so that you can impart
a very large acceleration on it; this will make up for the lower mass and still result in a large force. This
time, you get the ball accelerated for sure, but your aim is wild. The ball rockets down the lane, but rolls
into the gutter, and then skips over into the next lane.
This is not working well. You play it safe for your next attempt, and gently roll your ball down the lane. It
heads straight for the pins, but is lacking in both mass and acceleration. The first couple of pins get
knocked over, but the force is lacking and the ball sort of grazes off the others—not so great.
Your friend takes a turn. Her forearm is huge and you can tell she has had a lot of practice. She imparts a
great acceleration to her massive bowling ball, sending it exactly where she wants it. The combined mass
and acceleration of the ball result in a force on the pins so large that they are simply blasted off the lane.
All the pins are down for a strike, and she sits down and relaxes while you take your next turn. This will be
a long game!
Student Guide (continued)
Lab Procedure
Here is an outline of the steps you should follow to plan your investigation for each part of this lab. Later
in the guide, you will have writing space to develop your ideas, collect data, analyze and discuss results,
and draw conclusions. Run through these steps twice, once for each of Newton’s laws.
Step 1: Devise an experiment to demonstrate Newton’s first or second law.
Develop the main steps and how you will run each experiment. You will have a car, a track, and
other possible materials as suggested by your teacher. How can you use them to develop
experiments that demonstrate Newton’s first and second law? There is room provided in this lab
guide to develop an experiment for each law. Develop the basic procedures and how you will
run the experiments in order to determine the materials you will need for each.
Part I: Newton’s first law is also called the law of inertia. How can you manipulate your toy car or
other materials to show that objects in motion tend to stay in motion and objects at rest tend to
stay at rest? Focus this experiment on demonstrating inertia.
Part II: Newton’s second law can be summarized as F = ma, or force equals mass times
acceleration. In this part, you will want to focus the experiment on changing one of the variables
in order to see a change in another.
Step 2: Determine the types of data you will gather and what tools of measurement will be used
to collect the data.
How will you gather data for your experiment? If gathering quantitative data, you may want to
devise a table in which you can record your results in an organized manner. Also, consider how
you will record any qualitative or descriptive data in addition to your numerical results.
Step 3: Gather materials and set up your experiment.
Now that you know what you will do, gather the necessary items. Besides the objects you will
experiment with, make sure you have the necessary equipment to take measurements. If you
are working with lab partners, make sure each person knows his/her role in running the
experiment. Check your setup and make sure everything is in order before you proceed.
Step 4: Run your experiment.
As you proceed with your experiment, make sure you record all the necessary data and that
each student is performing his/her role in running the experiment. Make sure all elements of
your experiment are complete. Do not forget to clean up when you are done!
Step 5: Use the Middle School Lab Report Guide to write your lab report.
Student Guide (continued)
Part I: Demonstrating Newton’s First Law of Motion
Step 1: Devise an experiment to demonstrate Newton’s first law.
Write the steps of your experiment.
Step 2: Determine the types of data you will gather and what tools of measurement will be used
to collect the data.
Make a list of the data sections or tables. List the tools or devices used to make measurements.
Student Guide (continued)
Step 3: Gather materials and set up your experiment.
Include a sketch of your experimental setup.
Step 4: Run your experiment.
Record your data and observations in the space below.
Step 5: Use the Middle School Lab Report Guide to write your lab report.
Student Guide (continued)
Part II: Verifying Newton’s Second Law of Motion
Step 1: Devise an experiment to verify Newton’s second law.
Write the steps of your experiment.
Step 2: Determine the types of data you will gather and what tools of measurement will be used
to collect the data.
Make a list of the data sections or tables. List the tools or devices used to make measurements.
Student Guide (continued)
Step 3: Gather materials and set up your experiment.
Include a sketch of your experimental setup.
Step 4: Run your experiment.
Record your data and observations in the space below.
Step 5: Use the Middle School Lab Report Guide to write your lab report
Table A: Baseline for Comparison
Height of ramp = 20____ cm
Mass of the car and washer = _92.2__ g Distance of car
(cm) Distance of washer
(cm)
Trial #1 255
Trial #2 242
Trial #3 245
Trial average 247 257
Table B: Demonstration of Newton’s First Law
Distance of car
(cm) Distance of washer
(cm)
Trial #1 75 225
Trial #2 75 185
Trial #3 75 191
Trial average 75 200.33
Qualitative
observations
None
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Part II: Newton’s Second Law
Table C: Demonstration of Newton’s Second Law
Number of washers Trial Time to travel 0.25 m
t1 (s) Time to travel 0.50 m
t2 (s)
1 washer
mass = __4.9_ g Trial #1 02.24 Average 03.16 Average
Trial #2 02.21 03.08
Trial #3 02.23 03.15
2 washers
mass = _9.8__ g Trial #1 01.94 Average 02.69 Average
Trial #2 01.95 02.72
Trial #3 01.87 02.42
3 washers
mass = _14.7__ g Trial #1 01.33 Average 01.88 Average
Trial #2 01.35 01.93
Trial #3 01.34 01.87
4 washers
mass = 19.6___ g Trial #1 00.81 Average 01.26 Average
Trial #2 00.95 01.39
Trial #3 00.88 01.34
Table D: Force of the Washers on the Car
Number of
washers Mass of washers
mw (g) Mass of washers
mw (kg) Acceleration due to
gravity
ag (m/s2) Force of gravity
on the washers
Fg (kg ● m/s2) Applied force
of washers
on the car
Fwc (kg ● m/s2)
1 4.9 0.0048 10 0.049 0.049
2 9.8 0.0098 10 0.098 0.098
3 14.7 0.0147 10 0.147 0.147
4 19.6 0.0196 10 0.196 0.196
�
Table E: Calculations of Acceleration
Number of
washers Initial velocity
(from 0 to 0.25 m)
v1 = 0.25 m / t1
(m/s) Final velocity
(from 0.25 to 0.50 m)
v2 = 0.25 m / (t2 – t1)
(m/s) Acceleration
a = (v2 – v1) / (t2 – t1)
(m/s2)
1 0.11 0.28 0.19
2 0.13 0.36 0.33
3 0.19 0.45 0.47
4 0.28 0.56 0.62
Student Guide (continued)
Step 4: Run your experiment.
Record your data and observations in the space below.
Part I: Demonstrating Newton's First Law of Motion
Data:
- Distance of car (cm):
Trial #1: 75
Trial #2: 75
Trial #3: 75
Trial average: 75
- Distance of washer (cm):
Trial #1: 225
Trial #2: 185
Trial #3: 191
Trial average: 200.33
Observations: None
Part II: Verifying Newton's Second Law of Motion
Data:
Number of washers:
- 1 washer (mass = 4.9 g):
Trial #1:
- Time to travel 0.25 m (t1): 02.24 s
- Time to travel 0.50 m (t2): 03.16 s
Trial #2:
- Time to travel 0.25 m (t1): 02.21 s
- Time to travel 0.50 m (t2): 03.08 s
Trial #3:
- Time to travel 0.25 m (t1): 02.23 s
- Time to travel 0.50 m (t2): 03.15 s
- 2 washers (mass = 9.8 g):
Trial #1:
- Time to travel 0.25 m (t1): 01.94 s
- Time to travel 0.50 m (t2): 02.69 s
Trial #2:
- Time to travel 0.25 m (t1): 01.95 s
- Time to travel 0.50 m (t2): 02.72 s
Trial #3:
- Time to travel 0.25 m (t1): 01.87 s
- Time to travel 0.50 m (t2): 02.42 s
- 3 washers (mass = 14.7 g):
Trial #1:
- Time to travel 0.25 m (t1): 01.33 s
- Time to travel 0.50 m (t2): 01.88 s
Trial #2:
- Time to travel 0.25 m (t1): 01.35 s
- Time to travel 0.50 m (t2): 01.93 s
Trial #3:
- Time to travel 0.25 m (t1): 01.34 s
- Time to travel 0.50 m (t2): 01.87 s
- 4 washers (mass = 19.6 g):
Trial #1:
- Time to travel 0.25 m (t1): 00.81 s
- Time to travel 0.50 m (t2): 01.26 s
Trial #2:
- Time to travel 0.25 m (t1): 00.95 s
- Time to travel 0.50 m (t2): 01.39 s
Trial #3:
- Time to travel 0.25 m (t1): 00.88 s
- Time to travel 0.50 m (t2): 01.34 s
Observations: None
Step 5: Use the Middle School Lab Report Guide to write your lab report.