Measurements

Question 1

Define a scalar quantity.

Answer 1

It is a physical quantity that has only a magnitude.

Question 2

Define a vector quantity.

Answer 2

It is a physical quantity that has both magnitude and direction.

Question 3

Define random error.

Answer 3

A random error is one that leads to measurements being scattered about a mean value with no fixed pattern.

Question 4

Define systematic error.

Answer 4

A systematic error is one that leads to measurements being consistently higher or consistently lower than the true value.

Question 5

Define accuracy.

Answer 5

Accuracy is the degree to which measurements approach the true value of the quantity being measured.

Question 6

Define precision.

Answer 6

Precision is the degree of how close measurements of the same quantity are to each other.

Question 7

To how many s.f should absolute uncertainty [𝚫x] , fractional/percentage uncertainty [𝚫x/x], and d.p for measured values be expressed?

Answer 7

absolute uncertainty [𝚫x]: 1 s.f
fractional/percentage uncertainty [𝚫x/x]: 1-2 s.f
measured value: same d.p as its absolute uncertainty

Question 8

How do you estimate the uncertainty of a measured value?

Answer 8

Take X as the measured value, 𝚫X = ½ (Xmax - Xmin)

Question 9

Define a homogeneous equation.

Answer 9

A homogenous equation is when both sides of an equation have the same resultant units.

Question 10

Define an SI base unit.

Answer 10

SI base units are a selection of fundamental physical quantities, from which all other physical quantities can be represented as a combination of SI Base Units.

Question 11

Define a derived unit.

Answer 11

Derived Units are defined as products or quotients of base units and are obtained as products of base units