physics lab report experiment 2b

7/29/2019 Physics Lab Report Experiment 2b

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Georgia Southern University

Laboratory Report in Physics

Course/Section: PHYS 2211A/ 1113A

Experiment 2 Date: 24 January 2013

Experiment Title: Acceleration of a Freely Falling Body

Name: Richard Garrison

Partners Names: John Demere and Robert Branch

Abstract:

Instructors Comments:___________________________________________________________

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Instructors Name:_______________________ Grade:________________________


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Abstract

Acceleration under the influence of gravity plays a crucial role in physics as it is important to be

able to predict and manipulate objects in free fall. In order to measure the acceleration of a

freely falling body under the influence of gravity an experiment was set up to calculate it in two

different ways. The first being done by dropping a projectile and calculating its acceleration and

the second being done by calculating the projectiles velocity, graphing the results, and finding

its slope (the slope of the best fit line is acceleration). A timing mechanism was set up to

measure the time it took for a steel ball to strike a pressure sensitive timer from varying

heights. Acceleration was then calculated by manipulating the following equation. The

experiment returned the following results. The experiment would produce an average

acceleration rate of 9.78 m/s^2. Although this is not the accepted value of acceleration the

slope of the graph which displays the results confirm that 9.8 m/s^2 is in fact an accurate value.

The standard deviation for the experimental acceleration values was 0.12, while the percent

error was 0.20%.

Data

Table 1. Determining Acceleration

Trails Time

(seconds)

Acceleration

(m/s^2)

1 0.38 s 13.85

2 0.44 s 10.33

3 0.32 s 19.534 0.32 s 19.53

5 0.41 s 11.89

Distance the Ball Fell = _____________1.00____________m

Average Acceleration = ______________15.03______________m/s^2

Table 2. Velocity/Time Relations

Trials Time(seconds)

Distance(m)

Vfinal(m/s)

1 0.38 1.00 5.26

2 0.28 0.85 6.07

3 0.25 0.70 5.60

4 0.25 0.55 4.40

5 0.18 0.40 4.44


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6 0.15 0.25 3.34

7 0.12 0.10 1.67

Calculations

Acceleration can be calculated by rearranging the following equation.

Since yo and vo are zero according to the experiment the following calculation can be used to

determine acceleration from the data previously gathered.

, and therefore .Computing values to be entered in Table 1 gives us,

Trial 1

Trial 2

Trial 3

Trial 4

Trial 5

Solving for the average acceleration gives us,


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Calculating for standard deviation gives us,

Computing for percent error gives us,

Computing values to be entered in Table 2 gives us,

Trial 1

Trial 2

Trial 3

Trial 4

Trial 5

Trial 6


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Trial 7

Based on the slope of the Vfinal vs Time Graph, the percent error is as follows, Questions

1. What is the significance of the slope and y intercept of Vfinal vs Time graph? Give valuesof both.

After making a graph of my results a plotting a best fit trendline I was able to determine the

slope to be 9.8011. This is significant because the accepted acceleration rate of any object nearEarth under the influence of gravity is 9.8 m/s^2. It is also significant because the equation for

acceleration is

The slope is acceleration because a slope is

. The y intercept of the graph is -0.0056. I suspectthat this is actually the initial velocity, but it is so negligible that it can be assumed that the

initial velocity is 0.

2. Are the graphs linear, parabolic, or hyperbolic? (a) Vfinal vs Time (b) Distance vs TimeBoth graphs appear to be of linear behavior as the graphs represent equations for a constant

acceleration body.

Exercise

On the surface of the moon the acceleration due to gravity is about 1/6 the value on the Earth.

An object weighing 12 N weighs how much on the moon?

The commonly accepted rate of acceleration on Earth is 9.8 m/s^2 so converting a 12N object

to the moons possible rate would be given in the following calculations


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is the acceleration due to gravity on the moon. Keep in mind that theobject has a mass of 1.22kg found by manipulating the equation F=ma (

). Therefore onthe moon the object weighs .Conclusion

By conducting the experiment I calculated that the average acceleration rate due to

gravity was actually 9.78 m/s^2 as compared to the accepted value of 9.8 m/s^2. Although

possible error in the experimental value is attributed to faults within the timing mechanism, it

should be noted that the slope of the Vfinal vs Time graph is actually 9.8011 m/s^2. This

concludes that although there is slight error in the results, they are still precise enough to prove

that acceleration due to gravity is closer to the accepted value. The standard deviation for the

experimental acceleration values was 0.12, while the percent error was 0.20%. The percent

error for the slope of the Vfinal vs Time Graph was only 0.01%


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Graphs

y = 9.8011x - 0.0566

R = 0.9979

0

0.51

1.5

2

2.5

3

3.5

4

4.5

5

0 0.1 0.2 0.3 0.4 0.5

Vfinal(m/s)

Time (seconds)

Vfinal vs Time

Trials

Linear (Trials)

y = 2.9253x - 0.3927R = 0.9728

0

0.2

0.4

0.6

0.8

1

1.2

0 0.1 0.2 0.3 0.4 0.5

Distance(meters)

Time (seconds)

Distance vs Time

Trials

Linear (Trials)

physics lab report experiment 2b

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