In this experiment, the coefficient of static friction (s) between a wooden block and granite plane was determined. The coefficient of static friction (s) between the wooden block and granite plane was found to be 0.396 0.0001. The experiment was rather precise as the readings were quite close to the line of best fit when the readings were represented graphically. However, there certainly are sources of error in the experiment.
Sources of Error
1. Uncertainty in the triple beam balance (0.05g) might have affected mass measurements.
2. The smallest mass that could be added to the hanging masses, in order to increase the tension on the wire and therefore the force acting on the (wooden block + masses), was 10g. This caused error in the experiment because the wooden (block + masses) might have started moving when a mass between 0g and 10g was added to the hanging masses.
3. Human parallax error in taking mass measurements: the scale of the triple beam balance might not have been viewed at right angles.
4. The difficulty in determining the instant at which the block started to move. The block moved so slowly that one did not always immediately notice its motion. 5. We assumed that at the instant of motion the frictional force acting on the block is equal to the weight of the hanging masses. This assumption causes error in the readings because at the instant of motion the weight of the hanging masses is slightly greater than the frictional force acting on the block. 6. Not taking a conducting a sufficient number of trials.
Improvements
1. Using a more accurate balance: e.g. a digital balance. 2. Replacing the hanging masses with a container in which sand or water can be poured until the (block + masses) starts moving. The mass of the sand or water in the container is then found and divided by the mass of the (block + masses) to find the coefficient of static friction. This is likely to yield more accurate results because the exact hanging mass needed to move the block is determined by using this method.
3. Placing a photogate connected to a lamp or bell exactly in front of the (block + masses). When the block moves, however slightly, the lamp would light up or the bell would start ringing to indicate the motion of the (block + masses). 4. Making sure the scale of the balance is always viewed at a right angle to avoid parallax error. 5. Conducting more trials and taking the average result in order to minimize the affects of random error.