Scalars And Vectors and graphs

Question 1

Scalar quantities

Answer 1

A physical quantity is something that can be measured. Scalar quantities only have a magnitude or size.

Question 2

Examples of scalar quantities

Answer 2

temperature, eg 10 degrees Celsius (°C)
mass, eg 5 kilograms (kg)
energy, eg 2,000 joules (J)
distance, eg 19 metres (m)
speed, eg 8 metres per second (m/s)
density, eg 1,500 kilograms per metre cubed (kg/m³)

Question 3

Adding scalars

Answer 3

The sum of scalar quantities can be found by adding their values together

Question 4

Subtracting scalars

Answer 4

Scalar quantities can be subtracted by subtracting one value from another.

Question 5

Vector quantities

Answer 5

Vector quantities have both magnitude and an associated direction. This makes them different from scalar quantities, which just have magnitude.

Question 6

Examples of vector quantities

Answer 6

force, eg 20 newtons (N) to the left
displacement, eg 50 kilometres (km) east
velocity, eg 11 metres per second (m/s) upwards
acceleration, eg 9.8 metres per second squared (m/s²) downwards
momentum, eg 250 kilogram metres per second (kg m/s) south west

Question 7

resultant force

Answer 7

The resultant force is a single force that has the same effect as two or more forces acting together. You can easily calculate the resultant force of two forces that act in a straight line.

Question 8

Two forces in the same direction

Answer 8

Two forces that act in the same direction produce a resultant force that is greater than either individual force. Simply add the magnitudes of the two forces together.

Question 9

Two forces in opposite directions

Answer 9

Two forces that act in opposite directions produce a resultant force that is smaller than either individual force.

Question 10

Free body diagrams and vector diagrams

Answer 10

Free body diagrams are used to describe situations where several forces act on an object. Vector diagrams are used to resolve (break down) a single force into two forces acting at right angles to each other.

Question 11

Displacement

Answer 11

Distance without a change in direction

Question 12

Magnitude

Answer 12

The size of a quantity

Question 13

Tangent

Answer 13

a straight line drawn to touch a point on a curve so it has the same gradient as the curve at that point