## 1.18 know and use the relationship between weight, mass and gravitational field strength: W=mxg

Weight (N)= Mass (kg) x gravitational field strength (N/kg)

gravitational field strength on earth is approx. 10 N/kg and in GCSEs is taken to be 10 N/kg.

## 8.01 use the following units: kilogram (kg), metre (m), metre/second (m/s), metre/second2 (m/s2), newton (N), second (s), newton/kilogram (N/kg)

units for:

Mass: kilogram (kg)

distance: metre (m)

velocity: metre per second (m/s)

acceleration: metre per second squared (m/s2)

Force: newton (N)

time: second (s)

gravitational field strength: newton/kilogram (N/kg)

2019-06-28T10:23:24+00:00Categories: 8 Astrophysics, 8(a) Units, Edexcel iGCSE Physics, Uncategorized||

## 8.02 know that: the universe is a large collection of billions of galaxies, a galaxy is a large collection of billions of stars, our solar system is in the Milky Way galaxy

The  Milky Way galaxy contains billions of stars

The Universe – billions of galaxies

## 8.03 understand why gravitational field strength, g, varies and know that it is different on other planets and the Moon from that on the Earth

 An object’s gravitational field strength depends on its MASS. A massive object, like a star, will have a very large g-field. The Moon has less mass than the Earth, so its gravitational field is much weaker – approx 1/6th of the Earth’s. This means that we could jump higher on the Moon, and objects would fall more slowly, as they experience a weaker gravitational force.   A planet with a large radius will have a weaker gravitational field at its surface, because the surface is further away from the centre of the planet.

## 8.04 explain that gravitational force: causes moons to orbit planets, causes the planets to orbit the Sun, causes artificial satellites to orbit the Earth, causes comets to orbit the Sun

According to Newton, there is an attractive gravitational force between any two objects– pulling them together. E.g. the planets and comets experience an attractive force towards the Sun.

Moons and artificial satellites are attracted to their planets, and so are pulled towards them.

This gravitational force keeps them moving in curved paths called orbits. The Moon does not crash into the Earth, and the planets do not crash into the Sun because they are moving.

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Section 1: Principles of chemistry

a) States of matter

b) Atoms

c) Atomic structure

d) Relative formula masses and molar volumes of gases

e) Chemical formulae and chemical equations

f) Ionic compounds

g) Covalent substances

h) Metallic crystals

i) Electrolysis

Section 2: Chemistry of the elements

a) The Periodic Table

b) Group 1 elements: lithium, sodium and potassium

c) Group 7 elements: chlorine, bromine and iodine

d) Oxygen and oxides

e) Hydrogen and water

f) Reactivity series

g) Tests for ions and gases

Section 3: Organic chemistry

a) Introduction

b) Alkanes

c) Alkenes

d) Ethanol

Section 4: Physical chemistry

a) Acids, alkalis and salts

b) Energetics

c) Rates of reaction

d) Equilibria

Section 5: Chemistry in industry

a) Extraction and uses of metals

b) Crude oil

c) Synthetic polymers

d) The industrial manufacture of chemicals