Physics Topic 1: Measurements and Their Errors

Q": What are the SI base units for mass, length, and time?

• Mass: kilogram (kg)

• Length: metre (m)

• Time: second (s)

Q: What is meant by the resolution of a measuring instrument?

A: The smallest change that a measuring instrument can detect.

Q: What is absolute uncertainty?

A: The margin of error in a measurement, usually equal to the smallest division on the measuring instrument.

Q: What is percentage uncertainty?

A: A measure of uncertainty relative to the size of the measurement, calculated as
(absolute uncertainty ÷ measured value) × 100.

Q: What is the difference between accuracy and precision?

A: Accuracy is how close a measurement is to the true value, while precision is how consistent repeated measurements are.

Q: What are random errors?

A: Errors that vary unpredictably between measurements, often due to environmental factors or human reaction time.

Q: What are systematic errors?

A: Errors that are consistent and repeatable, usually caused by faulty equipment or incorrect calibration.

Q: How can random errors be reduced?

A: By taking multiple readings and calculating the mean.

Q: How can systematic errors be reduced?

A: By calibrating instruments, checking for zero errors, and using reliable procedures.

Q: How do you combine uncertainties when adding or subtracting?

A: Add the absolute uncertainties of each quantity.

Q: How do you combine uncertainties when multiplying or dividing?

A: Add the percentage uncertainties of each quantity.