- Level: International Baccalaureate
- Subject: Physics
- Word count: 1882
IBPhysics - Circular Motion Lab -MedepalliD
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Introduction
Dhruv Medepalli – Circular Motion Lab pg
Circular Motion Lab
DESIGN
Aspect 1 – Defining the problem and selecting variables
Problem: How does a change in the length of the radius affect the velocity of the stopper?
Research:
Circular motion can be expressed in terms of formulas as it directly links to Newton’s 2nd law, f=ma.
Fc = m*a
This relates to circular motion as in circular motion:
Because f= m*a
We can say that:
Frequency = number of revolutions per second
Variables
Independent variable(s) (manipulated):
- Radius
Dependent variable(s) (measured):
- Velocity
Controlled variable(s) (constant):
- Human Error
- Friction
- Air resistance
- Technology
Aspect 2 – Controlling variables
The variables were controlled in the following ways:
Independent:
- Radius- during the Experiment that we conducted our independent variable that we controlled was the radius. We controlled the radius length which affected the rev/s during our lab and based on that we gathered our data.
Controlled:
- Human Error- controlling human error played a major role in our lab. This was because the timer tried to reduce error by gathering exact time. We reduced the error and got a more precise time by conducting three trials per radius length.
- Friction- In this lab we assumed that there was no friction
- Air resistance- In this lab we assumed there was no air resistance
- Technology- In our lab, the major piece of technology that we used was the stopwatch. The stop watch that we had received was hard to use and had a slow reaction time. There would be error in the time between when we stopped the experiment and we stopped the timer as the timer was a slow reactor.
Aspect 3 – Developing a method for collection of data
- Gather all the materials which included:
- 1 hanging mass
- 1 stopper
- 1 meter stick
- 1 piece of string
- 1 test tube
- 1 marker pen
- Record the mass of the hanging mass and the stopper
- Create ones table
- Mark the 30cm,40cm,50cm,60cm, and 70 cm lengths on the string
- Place tube through the string
- Tie the string to the hanging mass and tie the stopper to the string
- Practice swinging the stopper with one hand holding the tube
- When you have got the hang of it, take your first cm and make sure it is a the rim of the tube
- Begin timing and count to 20 revolutions and stop
- Take down the time in which it took to do 20 revolutions
- Repeat steps 7-10 with the other measurements
Lab setup:
DATA COLLECTION AND PROCESSING
Aspect 1 – Recording raw data
Uncertainties
- Centimeters: 1cm ± .05cm
- Time: 1s ± .005s
- Mass: 1kg ± 0.000005kg
Middle
70± .05cm
1.35 ± 0.02
1.37 ± 0.02
1.36±0.02
How to Convert into m/s -1
Rev/s* 2𝛑r
2.13±.02 * 2𝛑r
2.13 (2) (𝛑) (.3)
= 4.01
±.02* 2𝛑r
= ±.04
Table of m/s -1
Radius ± .05cm | m/s-1 Trial 1 | m/s-1 Trial 2 | m/s-1 Trial 3 |
30± .05cm | 4.01±0.04 | 3.56±0.04 | 3.93±0.04 |
40± .05cm | 4.42±0.04 | 4.59±0.04 | 4.52±0.04 |
50± .05cm | 4.99±0.04 | 5.18±0.04 | 5.30±0.04 |
60± .05cm | 4.89±0.04 | 5.53±0.04 | 5.76±0.04 |
70± .05cm | 5.93±0.04 | 6.02±0.04 | 5.97±0.04 |
Average Velocity of m/s-1
Radius ± .05cm | Average Velocity of m/s-1 |
30± .05cm | 3.83±0.04 |
40± .05cm | 4.51±0.04 |
50± .05cm | 5.16±0.04 |
60± .05cm | 5.39±0.04 |
70± .05cm | 5.97±0.04 |
Conclusion
Aspect 3 – Improving the investigation
With reference to Aspect to where it states that an abundance of time was given; we could have taken more trails and got our data even more precise, it would have been really fun to see what would happen if the radius got much smaller and if the radius got a whole lot bigger. In the future we could definitely get better stop watches which would help a lot more. With stop watches being a major deal, another person good have joined the group and more times could have been taken per trial which would make the data reduced of errors greatly.
Dhruv Medepalli – Circular Motion Lab pg
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