Chapter 2 foundations Flashcards
What are the SI base units for mass, length, time, and electric current?
Mass: kilogram (kg)
Length: metre (m)
Time: second (s)
Electric current: ampere (A)
What is the SI base unit for temperature?
Kelvin (K)
What is the SI base unit for the amount of substance?
Mole (mol)
What is the SI base unit for luminous intensity?
Candela (cd)
What does a vector quantity have that a scalar quantity does not?
Direction
Give three examples of scalar quantities.
Speed, distance, energy
Give three examples of vector quantities.
Velocity, displacement, force
What is meant by ‘derived units’?
Units formed by combining base units (e.g. N = kg·m/s²)
Example: Newton is a derived unit.
How is the newton (N) defined in base units?
1 N = 1 kg·m/s²
Define accuracy.
How close a measurement is to the true value.
Define precision.
How close repeated measurements are to each other.
What is a systematic error?
An error that is consistent and affects all measurements in the same way (e.g. zero error).
Example: Zero error.
What is a random error?
An error that varies unpredictably from measurement to measurement.
How can you reduce random errors?
Take multiple measurements and calculate a mean.
What is the equation for percentage uncertainty?
(Absolute uncertainty ÷ measured value) × 100%
How do you find the uncertainty in a gradient from a graph?
Draw lines of maximum and minimum reasonable gradient, then compare them.
What is meant by significant figures?
Digits in a number that contribute to its precision.
