physical quantity

base quantities

derived quantity

a physical quantity that is not
dependent on other physical quantities

a physical quantity that is dependent
on other physical quantities

some base quantities
mass
amount of substance
length
time
temperature
electric current
light intensity

some derived quantities
displacement
area
volume
speed
velocity
work
energy
density

vector quantities

scalar quantities

a quantity that has both
magnitude and direction

a quantity that has only magnitude

some scalar quantities
distance
speed
mass
time
energy
volume
pressure
density

some vector quantities
displacement
velocity
acceleration
momentum
force

example:
5cm (distance)

example:
5cm to the right (displacement)

calculating vectors

by calculation

graphically

steps:

Choose a scale which fits the page For example, use 1 cm = 10 m or 1 cm = 1 N, so that the diagram is around 10cm

Draw the vectors at right angles to one another.

Complete the rectangle.

Draw the resultant vector diagonally from the origin.

Carefully measure the length of the resultant vector.

Use the scale factor to calculate the magnitude.

Use the protractor to measure the angle.

example:
035FE423-82E3-4D8E-BCB2-500926799C1F

PYTHAGORAS' THEOREM (hyp)² = (adj)² + (opp)²

steps:

  1. draw a vector diagram
  1. Calculate the magnitude of the resultant vector, using Pythagoras' Theorem.
  1. Calculate the direction of the resultant vector using trigonometry.
  1. State the final answer completes with direction.

Mass and weight

mass

weight

Mass is a measure of the quantity of matter in an object at rest relative to the observer.

mass is a scalar quantity

SI units: Kilogram (Kg)

for every Kg, there is 1000 grams

weight is a gravitational force on an object with mass

weight is a vector quantity

Si units: Newtons (N)

because of weight:

objects will always fall to the ground

objects stay firmly on the ground

satellites are kept in orbit

the weight of a body is equal
to the product of its mass (m) and the
acceleration of freefall (g) 088B3EEF-D7A6-487B-9647-B788AA095B97

we can find the mass of an object by using a scale

gravitational field strength

the force per unit mass acting on an objectin a gravitational field on earth

this is equal to 9.8N/Kg

density

mass per unit volume of a material 5206D8EA-F411-4486-A2C5-6C8058776388

mass is found by using a scale

volume can be found by calculating with the appropriate equation if the shape is regular, or using a measuring cylinder ed with water for irregular objects

volume of a cube: L x W x H

volume of a cylinder: πr² x H

vomule of sphere: 4/3πr³