# Newton's Laws Procedure Part A Newton's Second Law and

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Newton’s Laws
Procedure

Part A: Newton’s Second Law and Momentum
This part of the experiment will use air tracks and photogates. The
computers should already be turned on however, in the event that they are oﬀ
turn on the Science Workshop Model 750 Interface box. The on/oﬀ switch
is found on the back side of the interface. A green LED will light indicating
that this has been done. If this is not done ﬁrst, the computer will be unable
to communicate with the interface. In this event, shut down the computer
and start over.
Steps 1 - 5 should have already been completed for you. Please start the
procedure at step 6.

1. Plug the photogates into Channels 1 and 2 of the Science Workshop
interface. After the interface and the computer are turned on, double
click on Data Studio.

2. Click on Create Experiment.

3. In the Experiment Setup window scroll down to Photogate and double
click. Note that a photogate icon appears under Digital Channel 1 on
the picture of the Science Workshop Model 750 interface. Repeat this
step so that a second photogate icon appears under Digital Channel 2.

4. In the Data window, double click on Time between Any Gates, CH 2
(s). When the Data properties screen appears, click on OK.

5. In the Displays window, double click Digits, then Time between Any
Gates, CH 2 (s) and then click on OK.

6. Raise the scissor jacks on the end of the air track so that the bottom
of the track is 10.0 cm above the table.

7. Locate the two photogates attached to the interface box. Place these
photogates 30.0 cm away from one another over the air track. Make sure
that when the cart goes through this gate it obstructs the photogate
beam and the red LED lights up.

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8. Add 20.0 g to the air cart.
9. Find the mass of the air cart with the 20.0 g by placing it on the
balance. Convert this value to kg and record above Data Table 1a.
10. Place the air cart at the top of the track so that it is just touching the
bumper.
11. Click Start on the computer.
12. Turn the air blower on (a setting of 2 - 3 works best) and hold on to
the air cart.
13. Release the air cart from rest and allow the air cart to glide through
both gates.
14. Record the time interval on Data Table 1a in the row appropriate for
the distance between the gates.
15. Repeat step 10 through 14 two more times.
16. Move Photogate 2 30.0 cm further down the track so that the total
distance between the gates is now 60.0 cm. The Photogate may need
to be readjusted to ensure that the cart will cut oﬀ the beam.
17. Keep the mass of the cart the same and repeat steps 10 through 15 for
this new distance.
18. Repeat steps 10 through 15 increasing the distances between the gates
to 90.0 cm and 120.0 cm respectively.
19. Repeat Steps 10 - 18 with the addition of 20.0 g to the cart for a total
of 40.0g on the cart, and then repeat the experiment again for a total
of 100.0 g on the cart. Make sure to ﬁnd the mass of the cart with
the additional masses added and record all data for this portion of the
experiment in Data Table 1b and Data Table 1c respectively.
20. Change windows on the computer to the Spreadsheet and input the
data for Table 1a, Table 1b, and Table 1c. The computer should then
do the calculations for average time, velocity, and acceleration. Feel
free to save this ﬁle on the computer in case of any problems. DO

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Part B: Newton’s Third Law and the Conservation
of Momentum
Steps 1 - 6 for this part of the lab have been performed for you and are
found in a ﬁle on the desktop. Please close out of the previous screen by
clicking on ﬁle in the main screen and scrolling down to Exit. Then double
click on the appropriate ﬁle name given to you by the instructor. Start at
step 7.

1. Make sure Data Studio is on the computer screen. Close out of the
previous experiment by clicking on ﬁle in the main screen and scrolling
down to New Activity and clicking once. A box should appear and ask
if you wish to save the previous experiment. Click on NO.

2. In the Experiment Setup window scroll down to Photogate and double
click. Note that a photogate icon appears under Digital Channel 1 on
the picture of the Science Workshop Model 750 interface. Repeat this
step so that a second photogate icon appears under Digital Channel 2.

3. In the Data window, double click on Velocity in Gate, CH 1. When
the Data properties screen appears, click on OK.

4. Again, in the Data window, double click on Velocity in Gate, CH 2.
When the Data properties screen appears, click on OK.

5. In the Displays window, double click Digits, then Velocity in Gate,
CH1 and then click on OK.

6. Again, In the Displays window, double click Digits, then Velocity in
Gate, CH2 and then click on OK.

7. Lower the scissor jack from Part A to level the air track.

8. Place both photogates so that the distance between them is 60.0 cm.

9. Note that there are two air carts. Designate one air cart to always be
Air Cart #1 and the other to always be Air Cart #2.

10. Find the mass of both air carts. Record these values in Data Tables 2a
and 2b respectively.

11. Place Air Cart #2 directly between both photogates.

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12. Place Air Cart #1 to the left of the ﬁrst photogate.

13. Click Start on the computer and turn on the air blowers to the same
level as in Part A.

14. Send Air Cart #1 through the ﬁrst photogate and toward Air Cart #2.
The two should collide sending Air Cart #2 through the second gate.

15. The display for CH1 will have the initial velocity for Air Cart #1.
Record this in Data Table 2a under Before Collision Velocity.

16. The display for CH2 will have the ﬁnal velocity for Air Cart #2. Record
this in Data Table 2b as After Collision Velocity.

17. Repeat the experiment three more times using an additional 10.0 g,
20.0 g,and 40.0 g of mass on both Air Carts. Don’t forget to ﬁnd the
mass of both air carts with the additional mass for each new trial.

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Newton’s Laws
Analysis

Part A: Newton’s Second Law and Momentum

1. Use the formula below to calculate the momentum for each trial in
Tables 1a,1b, and 1c.

momentum = mass × velocity

Record these values in the appropriate Table (1a, 1b, or 1c).

2. Use the formula below to calculate the force for each trial in Tables
1a,1b, and 1c.
F orce = mass × acceleration
Record these values in the appropriate Table (1a,1b, or 1c).

3. Create a graph of Force vs. Acceleration for each Data Table (1a,1b,1c)
in Part A. Make sure to draw the best ﬁt line to the points of data.

4. Find the slope for each graph and record this value under the appro-
priate Data Table.

5. What does the slope of each graph represent? Explain your reasoning
below Data Table 1c.

6. Find the average force and average momentum for each set of data in
Tables 1a, 1b, and 1c. Record these values under the corresponding
Data Table.

7. Did the average force increase or decrease as the mass was increased?
Explain your reasoning below Data Table 1c.

8. Did the average momentum increase or decrease as the mass was in-
creased? Explain your reasoning below Data Table 1c.

9. What relationship can be ascertained between Newton’s Second Law
and momentum according to the answers of questions 7 and 8? Explain
your reasoning below Data Table 1c.

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Part B: Newton’s Third Law and the Conservation
of Momentum

1. Find the initial momentum for each trial for both Air Cart #1 and
Air Cart #2 using the aprropriate mass for the trial and the corre-
sponding before collision velocity. Record these calculations under the
appropriate column in table 2a and 2b.

2. Find the ﬁnal momentum for each trial for both Air Cart #1 and Air
Cart #2 using the appropriate mass for the trial and the corresponding
after collision velocity. Record these calculations under the appropriate
column in table 2a and 2b.

3. Determine the total initial momentum for each trial by adding Air Cart
#1’s initial momentum to Air Cart #2’s initial momentum. Record
these values in Data Table 2c.

4. Determine the total ﬁnal momentum for each trial by adding Air Cart
#1’s ﬁnal momentum to Air Cart #2’s ﬁnal momentum. Record these
values in Data Table 2c.

5. Find the % diﬀerence between the initial and ﬁnal momentum for each
trial. Record these values in Data Table 2c.

6. According to the % diﬀerences found in the previous question, do any
of the trials agree with the conservation of momentum? Consider this
a yes if the % diﬀerence is below 10 %. Explain why or why not below
Data Table 2c.

7. How does this experiment demonstrate Newton’s Third Law ? Record

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Energy
Procedure

Part A: Conservation of Mechanical Energy

1. Place photogates over the track on the table 30.0 cm from one another.

2. Place the 2.0 g ﬂag on top of the car.

3. Find the mass of the car plus the ﬂag. Convert this value to kg and
record in Data Table 1.

4. Measure the height from the table to the point where the car will be
released at the top of the track. Convert this value to meters and record
above Data Table 1.

5. Place the car at the top of the track and let the car go. Do not push
the car down.

6. Record the time interval from Photogate #2 in Data Table 1.

7. Repeat steps 5 and 6 for two more trials.

8. Take the 2.0 g ﬂag oﬀ of the car and repeat Steps 3 - 7 using the 4.0 g,
6.0 g, and 8.0 g ﬂags.

9. Use the spreadsheet on the computer and type in the values found for
the time for all of the masses. The spreadsheet will then automatically
ﬁnd the average time and velocity.

Part B: Work

1. Remove the photogates from the track and obtain a stopwatch.

2. Obtain the wood block found in the kit. Find the mass of the wood
block and record this value above Data Table 2 in kg.

3. Place the wood block at the bottom of the drop.

4. Place the 2.0 g ﬂag on the car.

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5. Find the mass of the car plus the ﬂag. Convert this value to kg and
record in Data Table 2.
6. Place the car at the top of the track and let the car go. Do not push
the car down.
7. The moment the car strikes the block start the stopwatch. Time this
event until the car and block come to rest. Record the time in Data
Table 2.
8. Measure the distance that the block was moved by the car. Convert
this value to meters and record in Data Table 2. Record this value in
Data Table 2.
9. Repeat steps 3 - 6 using the 4.0 g, 6.0 g, and 8.0 g ﬂags.

Part C: Simple Machines

1. Place a hanger on each side of the pivot.
2. Adjust the left hanger so that it is 20.0 cm from the pivot point. The
left hand side will be considered the Resistance side and the mass of
the hanger is given on Data Table 3 as the Mass of Resistance.
3. Adjust the right hanger by sliding it back and forth along the rod until
the two hangers balance. The right hand side will be considered the
Eﬀort side and the mass is given in Data Table 3 as the Mass of Eﬀort.
4. Record the distance in meters from the pivot to the right hanger as the
Measured Eﬀort Distance in Data Table 3.
5. Add 20.0 g to the resistance hanger.
6. Move the resistance hanger so that it is now 15.0 cm from the pivot.
7. Adjust the eﬀort hanger until the two hangers are balanced. Record
the distance in meters from the pivot as the Measured Eﬀort Distance
in Data Table 3.
8. Keep the mass of the resistance hanger and the eﬀort hanger constant
and repeat steps 6 - 7 using resistance distances of 10.0 cm and 5.0 cm.

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Energy
Analysis

Part A: Conservation of Mechanical Energy

1. Calculate the potential energy for each mass tested using the equation
found below and record the values in Data Table 1.

P.E. = (mass) × (g) × (height)

2. Calculate the kinetic energy for each mass tested using the equation
found below and record the values in Data Table 1.

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K.E. =     × (mass) × (velocity)2
2

3. Calculate the % diﬀerence between the potential energy and the kinetic
energy for each mass tested. Record these results in Data Table 1.

4. According to the calculated % diﬀerence from the preceding question
do any of the masses tested violate the Law of Conservation of Energy?
Consider anything above 10 % to be a violation. If so, why did this
occur and how can it be ﬁxed? (Never use human error as a viable
experimental error!!!)

Part B: Work

1. Find the acceleration of the wood block for each trial by using the
following formula:

2 × distance
accelerationblock =
(time)2

Record these values in the appropriate space in the Data Table 2.

2. Find the force of the car on the wood block for each trial using Newton’s
Second Law (make sure to use the mass of the wood block for each
calculation.) Record these values in Data Table 2.

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3. Calculate the work done on the block using the following formula:

workblock = f orce × distance

Record these values in the appropriates spaces in Data Table 2.

4. Pick one trial and calculate the power on the block by using the fol-
lowing formula:

workblock
power =
time

Convert to horsepower and record below Data Table 2.

Part C: Simple Machines

1. Calculate the Resistance Force and the Eﬀort Force by calculating the
weight for each mass respectively. Record these values in Data Table
3.

2. Find the theoretical value for each eﬀort distance (E.D.) by using the
following formula:

F orceresist.
E.D. = (                  ) × Resistancedistance
F orceef f ort

Record these values under calculated eﬀort distance in Data Table 3.

3. Calculate the % diﬀerence between the measured Eﬀort Distance and
the calculated Eﬀort Distance. Record these values in Data Table 3.

4. What type of simple machine would this set-up be considered? Explain
your reasoning in Part C of the Data Sheet.

5. Do any of the trials deviate from the concept that work-in should equal
work-out? If so why? Explain your reasoning in Part C of the Data
Sheet.

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