DEFINING NEWTON’S SECOND LAW
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Defining Newton’s Second Law
Name
School of Education, Liberty University
Experiment/Investigation Plan
Problem/Question: How does adding washers (mass) to the truck affect the rate (speed) at which it
travels down a ramp?
DEFINING NEWTON’S SECOND LAW
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Literature Review: Define Newtons Law’s Laws of motion and the law of force. Isaac Newton created
three laws of motion based on his observations about the world around him (Linde, 2020). His three
laws of motion deal with the relationships among force (energy needed to move an object measured
in Newtons), mass (amount of matter in a specified space), time, acceleration (how quickly an object
speeds up, slows down, or changes direction), and velocity (speed and direction) (DiLisi, 2019).
Newton’s first law of motion, also known as the Law of inertia, states “an object at rest remains at
rest, and an object in motion remains in motion at constant speed and in a straight line unless acted
on by an unbalanced force” (Hall, 2024, para. 3). Newton’s second law of motion, which states the
acceleration of an object depends on the mass of the object and the amount of force applied.
Understanding both laws, we can formulate an equation to determine that the force is equal to the
mass multiplied by the final velocity minus the initial velocity divided by the final time minus the
starting time. F=m*(V1V0) / t. The students will be conducting three trials each by adding mass
(washers) to a truck and investigating how the increase in mass affects the rate of speed at which the
truck travels down the ramp, then they calculate acceleration ((V1-V0)/t) from that data. The first trial
will be with the truck and no washers, the second trial will be with two washers on the truck, the
third trial will be by adding four washers on the truck, and the final trial will be by adding six washers
on the truck to correlate the mass amount to acceleration of the truck down the ramp. This will
further develop the understanding that adding mass to the truck will affect the rate and acceleration
on by which the truck will move down the ramp. This will be investigated so students can understand
the relationship between force, mass, and acceleration of an object.
Hypothesis: If we add washers to the truck then it will accelerate at a faster rate down the ramp thus
making the force higher.
Variables: Independent variable is the number of washers being added to each trial, and the
dependent variable is the amount of time (rate of speed) to get from one end of the plank to the
other end.
Controls: The plastic playmate truck, and the height and length of the ramp.
Materials:
(1) 3-foot ceder plank, sanded to reduce friction
DEFINING NEWTON’S SECOND LAW
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(4) Student textbook
(1) plastic playmate truck
(6) 1 oz Washer
(1) Stopwatch
(6) sticky notes
(1) video camera (phone camera)
(1) 1 paper to record time and intervals
Plan/Procedure:
The first step will be to build the ramp. One end of the cedar plank should be placed atop a stack of
four textbooks, and the other end on the ground.
Secondly take some post it notes and spread them 6 inches apart from the top of the plank to the
end of the plank. Ensure there is a timer available and a camera to capture any changes through
the experiment.
Start off with the playmate truck, without any washers, at the top of the ramp and let go of it.
Ensure to record the time from the beginning of the ramp to when it reaches the bottom of the
ramp.
This will be repeated 3 times to obtain an average calculation.
The second trial we will add 2 washers to the back of the truck, and like earlier, place the truck on
the top and record the time once it reaches the end of the ramp.
This will then be performed three more times to obtain an average time.
Repeat these steps until all six washers have been used in 2 washer increments.
Record the amount of time taken for each trial. To find the average take the four times for each
number of washers, add them up and divide by four.
Time Trials
Washers (oz) Time (sec) Observation
Vehicle 0 oz 119sec, 121sec,
122sec
Avg: (120.67sec)
The vehicle moved at normal pace as there was no
force (washers) being added to the back of the vehicle.
2 (2 oz) 103sec, 106sec,
107sec
Avg: (105.33sec)
The vehicle increased significantly with force being
applied to the back of the vehicle two washer (2oz).
4 (4 oz) 111sec, 111sec,
113sec
Avg: (111.67sec)
The vehicle decreased acceleration with four washers
(4 oz) even though there was a significant downward
force on the back end of the car.
6 (6 oz) 110sec, 109sec, When I added six washers (6oz) the time decreased
from
DEFINING NEWTON’S SECOND LAW
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110sec
Avg: (109.67sec)
the previous 4 oz trials, but wasn’t significant enough to
view with your eyes.
My analysis of the time trials measured how adding additional force (washers) affected the time
it took for the vehicle to complete its movement down the ramp. I conducted four trials,
starting with the car by itself and adding 2 ounces of weight per trial. Each of the conditions was
tested three times, as listed in Figure 1, and the average of each trial was also calculated to
determine the performance results listed in Figure 1.1.
Trial 1 Trial 2 Trial 3
90
95
100
105
110
115
120
125
Mass = Accerlation
0 oz 2 oz 4 oz 6 oz
T ime sec.
Figure 1
0 1 2 3 4 5 6
95
100
105
110
115
120
125
120.67
105.33 111.67 109.67
Average time
Time
Figure 1.1
DEFINING NEWTON’S SECOND LAW
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At 0 ounces, the vehicle had an average time of 120.67 seconds, representing the baseline
speed without any additional force being applied. The movement was described as normal,
indicating stable performance under no additional factors. When I added two washers, the
average time decreased to 105.33 seconds, indicating an improvement in the force applied
during the acceleration phase of the time trial. This suggests to me that the added weight
increased the vehicle’s traction and provided a small driving force, helping it move faster down
the course.
However, at four washers, the average time increased again to 111.67 seconds, meaning that
the vehicle became slower compared to the previous trial. This indicated that the added force
(washers) began to hinder performance, possibly due to the excessive load that reduced the
optimal downward force. Finally, at 6 ounces, the average time slightly improved to 109.67
seconds, a noticeable decrease compared to the previous trial. While heavier than previous
trials, the force being applied seemed to reach a point where it no longer produced a significant
performance difference.
Overall, the data collected showed that small amounts of force applied (washers) improved the
vehicle’s performance, but excessive weight began to slow it down. This led to the realization
that there is an optimal load where the car performs best.
Based on the data collected, it can be concluded that the amount of force being applied to a
vehicle directly affects its acceleration and amount of force. The experiment demonstrated that
adding small amounts of mass improved the vehicle's acceleration, while adding more caused
the truck to accelerate more slowly. This is evident in the average times compared between the
car with no weight and the first trial with 2 ounces of weight, which reduced the time from
120.67 seconds to 105.33 seconds. However, in the latter two trials, we observe that the
average times increased from the optimal trial using 2 ounces of weight.
These findings can be explained through Newton’s Second Law of Motion (F=ma). When optimal
mass is added, the acceleration slows (on average) in response. We stated the experiment with
independent variables of mass (washers in ounces) and the dependent variable was the time (in
seconds) required for the vehicle to move down the ramp. The results support the inference
that while adding some mass can improve vehicle force, too much slows the truck down and
impacts the amount of force. This experiment demonstrated that the relationship between
force and motion is not linear and that there is an optimal range of mass that can maximize the
vehicle’s acceleration, and therefore force. The data collected provides clear evidence that a
balance must be maintained between the applied force and the opposing forces to achieve
efficient motion.
DEFINING NEWTON’S SECOND LAW
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Reference:
DiLisi, G. A.(2019). Classical mechanics. Volume 3, Newton’s laws and uniform circular motion.
Morgan & Claypool Publishers. https://doi.org/10.1088/2053-
2571/ab1894
Hall, N. (Ed.). (2024, June 27). Newton’s laws of Motion. NASA.
https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/newtonslaws-of-motion/
Linde, B. M. (2020). Makerspace projects for understanding Newton’s law of motion. (1st
ed.). Rosen Publishing Group. https://ebookcentral.proquest.com/lib/liberty/reader.action?
docID=6237054&c=RVBVQg&ppg=1
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