AS OCR Physics planning exercise 2008

[Short1]

The manufacturers of wood floors need to know how much the wood expands and contracts with changes in humidity and temperature. One way of detecting expansion or contraction is to use a strain gauge.
You are required to design a laboratory experiment to investigate how the resistance of a strain gauge attached to a piece of wood varies with the temperature of the wood.
You should draw a diagram of the apparatus, and in your account you should pay particular attention to:
(a) the procedure to be followed
(b) how the strain gauge would be attached to the wood
(c) the range and precision of any instruments that would be used
(d) the factors that would need to be controlled to ensure that it is a valid test
(e) any safety precautions you would take when carrying out the experiment
(f) particular features of the design that would ensure the accuracy and reliability of your resultsI was just wondering if there is anyone on here that has done this planning exercise that could give me a little help on how to do it. I have looked all over the internet and not found any useful information at all, even on wikipedia. I am usually a pretty good physics student (got a B in forces and motion exam) but I just can't get my head round this. If anyone could provide a little help that would be great.

 

[jbsteele]

Diagram of Apparatus:The apparatus will consist of a strain gauge, wood sample and a thermometer. The strain gauge will be attached to the wood sample using adhesive tape. The thermometer will be placed next to the wood sample in order to measure the temperature of the wood.Procedure:1. Secure the strain gauge onto the wood sample using adhesive tape.2. Place the thermometer next to the wood sample.3. Measure the initial resistance of the strain gauge.4. Slowly increase the temperature of the wood sample until the desired temperature is reached.5. Measure the resistance of the strain gauge at each specified temperature.6. Record the data.7. Repeat steps 4-6 for different temperatures.Range and Precision of Instruments:The strain gauge should be able to measure the resistance of the wood sample with a high degree of accuracy and precision. An accurate thermometer should also be used in order to measure the temperature of the wood sample with a high degree of accuracy and precision.Factors to Control:It is important to ensure that the humidity level of the environment remains constant throughout the experiment in order to avoid any errors in the results. Additionally, the adhesive tape used to secure the strain gauge should not be allowed to move during the experiment.Safety Precautions:It is important to take all necessary safety precautions when carrying out this experiment. This includes wearing protective clothing and gloves, as well as ensuring that all electrical equipment is properly isolated.Design Features for Accuracy and Reliability:In order to ensure accuracy and reliability, the experiment should be repeated a number of times in order to get an average result. Additionally, the strain gauge should be calibrated before the experiment, and the thermometer should be tested for accuracy.

 

[Moetasim]

I am happy to assist you with your AS OCR Physics planning exercise. Here is a proposed experiment design for investigating how the resistance of a strain gauge attached to a piece of wood varies with temperature:

(a) Procedure:
1. Set up a wooden block on a stable surface.
2. Attach the strain gauge to the wooden block using adhesive or clamps.
3. Connect the strain gauge to a Wheatstone bridge circuit.
4. Place a thermometer next to the wooden block to measure the temperature.
5. Gradually increase the temperature of the wooden block using a heat source (e.g. hot plate or hairdryer).
6. Record the resistance of the strain gauge at different temperature intervals.
7. Repeat the experiment with the wooden block at different starting temperatures.
8. Plot the resistance of the strain gauge against temperature to observe the relationship.

(b) Attaching the strain gauge to the wood:
The strain gauge should be attached to the wooden block in a way that ensures it is in direct contact with the wood and can accurately measure any changes in its dimensions. Adhesive or clamps can be used to securely attach the strain gauge to the wood.

(c) Range and precision of instruments:
The thermometer should have a range of at least 0-100°C and a precision of 0.1°C. The Wheatstone bridge circuit should have a precision of 0.01Ω to accurately measure the resistance of the strain gauge.

(d) Factors to control for validity:
1. The starting temperature of the wooden block should be controlled for each trial to ensure consistency.
2. The strain gauge should be attached to the same area of the wooden block for each trial.
3. The heat source should be kept at a constant distance and angle from the wooden block to ensure consistent heating.
4. The strain gauge should be calibrated before each trial to ensure accurate measurements.

(e) Safety precautions:
1. Use heat-resistant gloves when handling the heated wooden block.
2. Keep the heat source away from any flammable materials.
3. Be cautious when handling the strain gauge to avoid damaging it.

(f) Features for accuracy and reliability:
1. Using a Wheatstone bridge circuit will provide accurate and precise measurements of the strain gauge resistance.
2. Conducting multiple trials at different starting temperatures will improve the reliability of the results.
3. Controlling for factors that could affect the results will ensure the accuracy of the experiment.