Calculating Percentage Error for a Circular Disc with (10 +/- 0.2)cm Radius

In summary, to determine the percentage error in the circumference of a circular disc with a radius of (10 +/- 0.2)cm, we need to use the error equation. The absolute error is found by dividing the absolute error of 0.2cm by the measurement of 10cm and multiplying by 100. We can then use the equation (error on C)^2 = ((dC/dA)*(error on A))^2 to find the absolute error on C, where C is the circumference and A is the radius.
  • #1
Boogeyman
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Homework Statement


A circular disc has a radius of (10 +/- 0.2)cm. Determine the percentage error in the determination of its circumference.

The Attempt at a Solution


I know that percentage error is found by absolute error divided by measurement x 100. The absolute error here is 0.2cm, and the measurement is 10cm. But what do I have to do with circumference?
 
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  • #2
Have you used the error equation before?

If we want to work out the absolute error on C and C = 3A, then,

(error on C)^2 = ((dC/dA)*(error on A))^2

From memory i think it's that. So imagine the circumference is C and make an equation for it. You should be able to get it from that.
 
  • #3


To determine the percentage error in the determination of the circumference, you will need to use the formula for circumference of a circle, which is C = 2πr, where r is the radius. Since the radius in this case is (10 +/- 0.2)cm, the circumference can be calculated as C = 2π(10 +/- 0.2)cm.

Using the formula for percentage error, the calculation would be:
Percentage error = (absolute error / measurement) x 100
= (0.2cm / 2π(10 +/- 0.2)cm) x 100
= 0.6% +/- 0.01%

Therefore, the percentage error in the determination of the circumference of the circular disc is 0.6% with an uncertainty of +/- 0.01%. This means that the actual circumference could be 0.01% higher or lower than the calculated value.
 

1. What is relative error?

Relative error is a measure of the difference between an estimated or calculated value and the true or exact value. It is expressed as a percentage or decimal, and is used to evaluate the accuracy of a measurement or calculation.

2. How is relative error calculated?

Relative error is calculated by taking the absolute value of the difference between the estimated value and the true value, then dividing it by the true value and multiplying by 100 to get a percentage. The formula is (|estimated value - true value| / true value) * 100.

3. What is the difference between relative error and absolute error?

Absolute error is the numerical difference between the estimated value and the true value, while relative error is the ratio of this difference to the true value. Absolute error is expressed in the same units as the measured quantity, while relative error is expressed as a percentage or decimal.

4. Why is relative error important in scientific experiments?

Relative error is important because it allows us to assess the accuracy of our measurements and calculations. It helps us understand how much our results deviate from the true value and can guide us in making improvements to our methods and equipment.

5. Can relative error be negative?

Yes, relative error can be negative. This occurs when the estimated value is greater than the true value, resulting in a negative difference. However, when calculating the percentage error, the absolute value of the difference is used to ensure a positive value is obtained.

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