Atwood LAB PDF

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AP Physics lab report utilizing the Atwood Machine, with explanations and data. ...

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Lab6 :Atwood’s Machine In this lab, you will determine the relationship between the two factors which influence the acceleration of an Atwood’s machine.

OBJECTIVES  Determine the relationships between the masses on an Atwood’s machine and the acceleration.

PROCEDURE Part I Keeping Total Mass Constant

For this part of the experiment you will keep the total mass used constant, but move weights from one side to the other 1. Set up the Atwood’s machine apparatus. Be sure the heavier mass can move at least 40 cm before striking the floor. 2. Arrange a collection of masses totaling 200 g on m2 and a 200 g mass on m1. What is the acceleration of this combination? Record your values for mass and acceleration in the data table. 3. Move 10 g from m2 to m1. Record the new masses in the data table. 4. Position m1 as high up as it can go. Steady the masses so they are not swinging. Wait one second and release the masses. Catch the falling mass before it strikes the floor or the other mass strikes the pulley. 5. Continue to move masses from m2 to m1, changing the difference between the masses, but keeping the total constant. Repeat this step until you get at least five different combinations. II. Keeping the mass difference constant

6. For this part of the experiment you will keep the difference in mass between the two sides of the Atwood’s machine constant and increase the total mass. 7. Put 90 g on m1 and 70 g on m2.

8. Repeat Steps 3 – 4 to collect data and determine the acceleration. 9. Add mass in 20 g increments to both sides, keeping a constant difference of 20 grams. Record the resulting mass for each combination in the data table. Repeat the procedure until you get at least five different combinations.

DATA TABLE Part I: Keeping Total Mass Constant Trial

m1 (g)

m2 (g)

Acceleration 2 (m/s )

m (kg)

mT (kg)

1

200

200

0

0

0.4

2

210

190

0.14

0.02

0.4

3

230

170

0.17

0.06

0.4

4

250

150

0.37

0.1

0.4

5

350

50

1.15

0.3

0.4

Part II: Keeping The Mass Difference Constant Trial

m1 (g)

m2 (g)

Acceleration 2 (m/s )

m (kg)

mT (kg)

1

70

50

0.60

0.02

0.12

2

90

70

0.22

0.02

0.16

3

110

90

0.25

0.02

0.20

4

170

150

0.18

0.02

0.32

5

210

190

0.14

0.02

0.4

ANALYSIS 10. For each trial, calculate the difference between m1 and m2 in kilograms. Enter the result in the column labeled m. 11. For each trial, calculate the total mass in kilograms. 12. Plot a graph of acceleration vs. m, using the Part I data. Based on your analysis of the graph, what is the relationship between the mass difference and the acceleration of an Atwood’s machine? As the mass difference increases, the acceleration also increases. There is fault in the graph as we take into account human error. The acceleration is increasing because mass 1 is larger and as that mass gets bigger the acceleration increases.

13. Plot a graph of acceleration vs. total mass, using the Part II data. Based on your analysis of the graph, what is the relationship between total mass and the acceleration of an Atwood’s machine? As the total mass starts to increase the acceleration decreases. The object is decelerating as you add more total mass because if you add more mass, because of the formula the acceleration would become smaller. There are some flaws in the graph due to human error and the reaction time when you stop the stopwatch.

14. Draw a free body diagram of m1 and another free body diagram of m2. Using these diagrams, apply Newton’s second law to each mass. Assume that the tension is the same on each mass and that they have the same acceleration. From these two equations, find an expression for the acceleration of m1 in terms of m1, m2, and g On other page 15. For each of the experimental runs you made, calculate the expected acceleration using the expression you found with Newton’s second law of motion and the specific masses used. Compare these figures with your experimental results. Are the experimental acceleration values low or high? Why? Expected Accelerations: Part I: Keeping Total Mass Constant Trial

m1 (g)

m2 (g)

Acceleration 2 (m/s )

m (kg)

mT (kg)

1

200

200

0

0

0.4

2

210

190

0.5

0.02

0.4

3

230

170

1.5

0.06

0.4

4

250

150

2.5

0.1

0.4

5

350

50

7.5

0.3

0.4

Part II: Keeping The Mass Difference Constant Trial

m1 (g)

m2 (g)

Acceleration 2 (m/s )

m (kg)

mT (kg)

1

70

50

1.67

0.02

0.12

2

90

70

1.25

0.02

0.16

3

110

90

1.00

0.02

0.20

4

170

150

0.63

0.02

0.32

5

210

190

0.5

0.02

0.4

The expected accelerations were much greater than the experimental accelerations because we did not take into account air resistance and the tensions of the pulley. The air resistance slows downs the pulley, also we assume that the tensions of the masses are equal. We also assume that the accelerations are equal for both sides....