Terminal Velocity Lab
Ryan Murray
Partners: Ryan Can, Ryan Stephen Leavy and Kevin Katzmann
AP Physics
Periods 1 & 2
October 24, 2010
Mrs. Keogh

Purpose : The purpose of this lab was to find the relationship between terminal velocity and mass through the use of coffee filters.
Setup Diagram : Eight coffee filters, a stopwatch to measure time, and a meter stick to measure distance were used in this lab.
Procedure : First, measure a reference height against an open wall that is anywhere above
1.5 meters and below 2.0 meters above the ground, and record this height ( 1.75 m ). Drop one coffee filter well above this height so that the coffee filter has had enough time to reach its terminal velocity. Time the coffee filter from when it reaches the reference height until it strikes the ground. Repeat this for a total of three trials and determine the average time. Calculate the terminal velocity for the coffee filter. Add another coffee filter onto the first one and repeat the procedure. Continue to add one more coffee filter and carry out three trials for each successive coffee filter added. Carry out a total of 8 trials of different numbers of coffee filters. Mass the coffee filters and determine the weight of the coffee filters for each of your trials.
Sample Calculations :
Average falling time for 1 coffee filter:
Average Time = (trial 1 time + trial 2 time + trial 3 time) / 3
Average Time = (2.75 s + 2.45 s + 3.05 s) / 3
Average Time = (8.25 s) / 3
Average Time = 2.75 s
Terminal velocity for 1 coffee filter:
V = d / t
V = 1.75 m / 2.75 s
V = 0.64 m/s
Data :
Number of filters
1
2
Trial 1
Time (s)
2.75
2.27
3
4
5
6
7
8
1.15
1.16
1.38
0.89
1.32
0.76
Graph : See attached.
Trial 2
Time (s)
2.45
1.80
1.76
1.59
1.49
1.38
0.80
0.75
Trial 3 time
(s)
3.05
2.32
1.26
1.20
0.90
1.16
0.70
0.67
Average
Time (s)
2.75
2.13
1.39
1.32
1.26
1.14
0.94
0.73
Terminal
Velocity
(m/s)
0.64
0.82
1.26
1.33
1.39
1.54
1.86
2.4

Conclusion Questions :
1.
Draw a freebody diagram of the forces acting on a single coffee filter as it falls to the ground with a terminal velocity. Label the forces and give their magnitudes.
2.
As more coffee filters are added, does the magnitude of the frictional force (air resistance) increase, decrease, or remain the same? Give a reason as to why this happens.
As more coffee filters are added, the magnitude of the frictional force (air resistance) increases heavier objects fall at a higher speed and terminal velocity, thereby increasing the amount of air that affects it on the way down and increasing the air resistance.
3.
There are two formulas which can be used to find the amount of air friction that acts on an object: a) Air Friction = (constant) x (velocity) b) Air friction = (constant) x (velocity)
2
Based on your graph, which formula above does this experiment support? Give evidence to support your answer.
Based on our graph, the experiment supports the second formula [Air friction =
(constant) x (velocity)
2
], as our graph is slightly curved (utilizing the line of best fit), and therefore representative of a parabola, indicating that variables would be squared, as is the case with the second formula.
4.
On the earth a hammer and a feather are dropped from a tall hill. Which hits the ground first? Why? If this activity were repeated on the moon, which would hit the ground first?
Why?
The hammer would hit the ground first on earth because it would have a higher velocity and gravity would act upon it with more force. However, on the moon, both would hit the ground at the same time as there is little to no air there and there is a lesser force gravity compared to the earth, thus little to no air resistance acting on both objects.
Conclusion : Terminal velocity increases as mass and weight increase as a result of decreased air resistance acting upon heavier objects and resulting in lesser total time for the fall.