Good General Knowledge to Survive Physics

Question 1

What are the fundamental SI Units?

Answer 1

Length (m), time (s), mass (kg), electrical current (Ampere - A), temperature (kelvin K), amount of a substance (Mole mol), luminous intensity (Candela (cd).

Question 2

Derived Units

Answer 2

Derived units are all other units that are derived from the fundamental SI units.

Question 3

What are significant figures?

Answer 3

Significant figures are the number of digits in a value, often a measurement, that contribute to the degree of accuracy of the value.

Question 4

Rules regarding significant figures

Answer 4

1. all non-zero digits are always significant
2. all final zeroes after the decimal point are significant
3. zeroes between two other significant digits are always significant 8008 –> 4 SF
4. zeroes used solely for spacing the decimal point are not significant eg. .0001 -> 1 SF

421 --> 3SF
4021 --> 4SF
6100 --> 2SF
610.0 --> 4SF
0.00102 --> 3SF

Question 5

Uncertainties - Precision

Answer 5

Precision is the degree of exactness to which a measurement can be reproduced.

Question 6

Uncertainties - Accuracy

Answer 6

The accuracy of a measurement describes how well the result agrees with an accepted value.

Question 7

Multiplying and Dividing Two Measurements

Answer 7

The number of significant digits in a product is the number in the factor with the lesser number of significant figures. For example 4.39/2.1 = 2.090476. Therefore, the answer is 2.1.

Question 8

Adding/Subtracting Two Measurements

Answer 8

Always use the least number of decimal places. For example, 22.1+2.36=24.46. Therefore, the answer is 24.5.

Question 9

Absolute Error

Answer 9

Absolute error is the actual difference between the measured value and accepted value. Absolute error = observed value - accepted value

Question 10

Relative Errors

Answer 10

The relative error is expressed as a percentage (called percentage error). E_r = Ea/A * 100%