[Neraphym]

>>Objective: The purpose of this lab was to calculate the average acceleration

due to gravity.


>>Hypothesis: The mass will fall at a rate slightly less than 9.8 m/s/s

(actual value of acceleration due to gravity) because of air resistance and

friction. The 500g mass would be effected by this to a lesser extent due to

momentum.


>>Materials: Tape Timer, Two 2m lengths of paper tape, timer stand, pad for

the mass to land on, 500g mass, 200g mass, and sticky tape.


>>Procedure:

1. Attatch the tape timer top of the timer stand. Secure the pole to the edge

of the workstation so that the tape will not hit the edge on the way down.

Place the pad where the mass will land.

2. Cut off 2 meter paper tape strips. Attatch a 200 g mass to one and a 500 g

mass to the other. Take the 200g tape strip and run the edge of the tape

through the tape timer so that the mass is right below the timer. Drop the

weight and the timer will mark the tape every 0.025 seconds. Repeat this with

the 500 g mass.

3. Measure the distance from the start of the tape to each subsequent ticker

marking. Record the measurements for both masses.

4. Determine the distances in between each ticker mark. Take these distances

and calculate the average velocity for each mark. Use this data to create a

graph and plot a best fit line. Determine the slope of the line to find the

average velocity. Do this for both masses, and compare the experimental

acceleration with the actual.


>>Calculations:

Change in Position = P2 - P1

Ex:
P1 = 0.75 cm
P2 = 1.35 cm

1.35 cm - 0.75 cm = 0.60 cm

Average Velocity = Change in Position / Time

Ex:
Change in Position = 1.45 cm
Time = 0.025 s

1.45 cm / 0.025 s = 58.0 cm/s

Average Acceleration = Change in Velocity (V2-V1) / Change in Time (T2 - T1)

200g Mass:
V1 = 140. cm/s
V2 = 380. cm/s
T1 = 0.2 s
T2 = 0.5 s

(38.0 cm/s - 140. cm/s) / (0.5 s - 0.2 s) = 800. cm/s/s

800. cm/s/s x 1m/100cm = 8.0 m/s/s

500g Mass:
V1 = 140. cm/s
V2 = 410. cm/s
T1 = 0.2 s
T2 = 0.5 s

(410. cm/s - 140. cm/s) / (0.5 s - 0.2 s) = 900. cm/s/s

900. cm/s/s x 1m/100cm = 9.0 m/s/s

Absolute Error = | Experimental Value - Accepted Value |

200g Mass:
Experimental Value = 8.0 m/s/s
Accepted Value = 9.8 m/s/s

| 8.0 m/s/s - 9.8 m/s/s | = 1.8 m/s/s

500g Mass:
Experimental Value = 9.0 m/s/s
Accepted Value = 9.8 m/s/s

| 9.0 m/s/s - 9.8 m/s/s | = 0.8 m/s/s

% Error = Absolute Error / Accepted Value

200g Mass:
Absolute Error = 1.8 m/s/s
Accepted Value = 9.8 m/s/s

1.8 m/s/s / 9.8 m/s/s x 100 % = 18.4 %

500g Mass:
Absolute Error = 0.8 m/s/s
Accepted Value = 9.8 m/s/s

0.8 m/s/s / 9.8 m/s/s x 100 % = 8.2 %


>>Conclusion

The objective of this lab was to determind the average acceleration due

to gravity. The result was a great deal lower than the actual value, however

my hypotheses was supported. Due to either error in the tape timer, drop

timing, friction, calculations or other possible sources of drag, the

experimental values (8.0 and 9.0 m/s/s) turned out to be lower than the actual

value (9.8 m/s/s). Because of the greater mass on the 500g mass when it was

dropped its momentum made the drag and friction less effective than that of the

200g mass'. To improve this lab, the test could be done multiple times and

averages of the tests could be taken, allowing for better, more precise

results. This has an infinite variety of applications to every day life. The

value of acceleration due to gravity is important when dealing with falling

objects. NASA has most definitely used this value to great extent when

calculating trajectories and shuttle speeds and a myriad of other calculations

involving physics.