Lab: Modeling the fall of an object falling with air resistance
Purpose:determine the relationship between air resistance force and speed. and model the fall of an object with air resistance.
Experiment:
Part 1
1.Model a relationship between air resistance force and speed.
take the logarithm of both sides
2.When an object has reached terminal velocity, the downward pull of gravity exactly balances the upward push of air resistance: Fnet=mg-Fair. When a=0, that is the object reach the terminal velocity, Fair=mg.
3.In laboratory, practice how to use Pro log to determine the terminal by taking a video of a coffee filter falling down a meter stick.
4.Take a set of coffee filters to Design Technology building. Drop 1-5 coffee filters from the second floor, increase the number of filters each time.
5.Take the video of the falling, and use the Pro log to determine the terminal velocity each time.
6.put in the Excel and graph the curve and get the equation of Fair and velocity.
Part 2
use the Excel to model the fall of an object with air resistance.
1.Set up the column of t, a, delta v, and v with A2=0, B2=9.8, C2=0, D2=0.
2.Input the formula =A2+0.01 into the cell A3.
3.Input the formula =B2*(A3-A2) into the cell C3.
4.Input the formula =D2+C3 into the cell D3.
5.Input the formula =9.8-0.07563/0.001*D3^1.764 into the cell.
6.Fill down the contents of Row 3 and find the velocity when a=0.
Results:
Part 1:
Based on the equation of the curve,
n=1.764 +/- 0.1816 k=0.007563 +/- 0.001291
Fair=0.007563*V^1.764
Part 2:
When mass=0.001kg. Velocity of measured is 1.142m/s, velocity of calculation is 1.164m/s.
When mass=0.004kg. Velocity of measured is 2.156m/s, velocity of calculation is 2.625m/s.
Conclusion:
Based on the equation of Fnet=mg-Fair, we can use the terminal velocity to find the relationship between air resistance force and speed.
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