Year 7 Science
Mass and weight
Weight
weight is the amount of pressure you apply to a certain area of the earth because of gravity. Weight is you mass times 10. Weight is measured in newtons.
Mass
Mass is the amount of matter in something it is measured in kilograms.
Forces
What is a force?
Types of forces
Gravity
Gravity is the force of attraction between two objects like a human and the earth.
Magnetism
Magnetic force attracts and repels different types of metals.
Friction
Friction occurs when two things rub against each other. Frictional force works by opposing motion.
Air resistance
When an object is moving quickly the air particles push against the object.
Bouyancy
Bouyancy makes an upwards push on a boat or something in the water.
static electricty
Electric charges a given off when certain objects rub against each.
Mixtures
What is a Mixture
A mixture is the product of 2 or more substances combined that can be relativly easily combined.
Methods of separation
Filtration and decanting
A method of separation for a mixture of a liquid and a solid. The sediment is left in the filter paper
Evaporation and crystallisation
This method is used by heating water untill it turns into a gas leaving behind the sediment.
Magnetism
If the mixture has metals that are attracted to a magnet in it magnetism can be used to remove them.
Distillation
Distillation evaporates water leaving behind impurities such as salt and cools the gas into liquid again.
Chromatography
The liquid soaks through the paper disolving substances on the paper. Some of them are absorb through the paper faster so its easier to tell which ones they are.
Separating funnel
A liquid that is less dense will float on top so when you slowy realese the more dense liquid the less dense liquid is left.
Centrifuging
By spinning the mixture quickly the solids go to the bottom straigt away.
The Greenhouse effect.
The Greenhouse effect
The greenhouse effect isn't bad. It is a natural way of heating. Radiation comes through and cannot escape through the atmosphere so it turns to heat.
The enhanced greenhouse effect.
The enhanced greenhouse effect works when radiation comes through the atmosphere and cant get out because of the carbon dioxide in the air so it warms the globe.