What is a force?
A force is something that exerts a push or pull or changes and objects shape.
What are forces measured in?
Forces are measured in newtons (N)
What is a field?
A field is said to exist when an object can exert a force on another object from a distance.
What is gravity?
It is an attractive force between objects
What factors does it depend on?
1) Mass of the objects
2) Distance between the objects
What do magnetic fields do?
Earth’s magnetic field helps us to navigate and to protect us from solar winds.
If the Earth lost its magnetic field it could kill all life on Earth.
Maxwell’s Electromagnetic Unifying Theory
- All matter is made out of atoms
- Atoms are made up out of positively charged nuclei and negatively charged electrons
- Therefore atoms have an electric field
- When electrons move through an electric field, electromagnetic radiation (EMR) is emitted
- The higher the frequency of the movement the higher the frequency of the EMR but in the form of a transverse wave
- The higher the frequency of the wave, the higher the energy the wave carries
- This EMR waves carries both an electric force and a magnetic force
- The wave travels at the speed of light
- Moving fields can transfer energy
What is a hypothesis?
a statement that explains something about the universe. It can either be true or false. It can be tested by experiments or observation. A hypothesis cannot be proven.
What is a law?
a robust, descriptive, normative statement that describes patterns of data.
What is a theory?
a comprehensive explanation or model of how some underlying principles of the universe works. Can be used to explain how laws work.
What is work?
Work is the movement of an object by a force.
What is the formula for work?
Work = force x distance
(Joule) (Newton) (metres)
(J) (N) (m)
What is energy?
Energy is the ability to do work
What is work done?
Energy transfer
What is the formula for energy transferred?
Energy = mass (kg) x specific heat x Temp
transferred capacity of H2O change (oC)
Where do energy transfers lose energy?
Heat
What is macroscopic energy?
The forms of energy we observe from outside the system (e.g. gravitational potential energy, kinetic energy etc.)
What is microscopic energy?
Energy at the molecular energy (e.g. energy in the chemical bonds, atom vibrations etc.)
Where does energy come from?
Albert Einstein linked microscopic energy with mass:
E=mc2
What are systematic errors?
- Errors involved with the system of the experiment
- These errors never go away when you repeat the experiment
- Can only be checked by repeating the experiment with different apparatus
- When systematic errors are small the data is said to be accurate
What are random errors?
- Inconsistent errors that can vary each time the experiment is done
- Better experimental design can help reduce random errors
- Best way to deal with these errors is to repeat the experiment several times and calculate the average results
- The range of data gives an indication of the size of the random error (e.g. error bars on a graph)
- Readings with small errors are said to be precise
What is mass?
Mass is a measurement of how much stuff is in an object. i.e. how many particles/atoms are in something. We measure this in kg.
What is acceleration?
Acceleration is the rate at which an object changes its velocity. We measure this in ms.
Acceleration = change of velocity/time
A = (V2 –V1) / t
Daltons Atomic Theory
- All matter is composed of atoms. Atoms are indivisible and indestructible (based on Democritus’ idea) but there is no knowledge of electrons, neutrons, protons or quarks etc.
- All atoms of a given element have the same mass (no knowledge of isotopes)
- Atoms combine to form compounds in simple whole-number ratios
- An atom of one element cannot change into an atom of another element - chemical reactions only involve rearrangement of atoms (no knowledge of nuclear reactions)
