Forces and Motion
What is the equation for average speed?
S=d/t
What 3 subatomic particles make up an atom
Protons
Electrons
Neutrons
Define frequency
The number of waves passing through a point per second
What are the two poles of a magnet?
North and south
What type of radiation is a wave of energy?
Gamma rays
What is meant by a scalar quantity? Give 2 examples
A quantity that has a magnitude only (or size)
How do diodes work?
A diode only allows current to flow in one direction
State the equation linking frequency and a period of a wave
frequency = 1/t
What is a permanent magnet?
A magnet that can produce its own magnetic field and it cannot be demagnetised.
What is meant by an isotope?
Atoms of an element that have the same number of protons but a different number of neutrons
State 3 ways a force can affect an object
- It can change its speed
- It can change its direction
- It can change its shape
What is meant by alternating current?
A current that changes direction 50 times a second
Explain red shifted and blue shifted
red shifted - shows and object is moving away because the red wavelength is longer so it is more visible
Blue shifted - shows and object is moving closer because the blue wavelength is shorter so it is more visible
Name four magnetic materials
Iron
Cobalt
Nikel
Steel
Explain the process of beta decay
- Neutron splits into a proton and an electron in the nucleus
- the electron is emitted from the nucleus to balance the atom
- this is a beta particle
It is the distance a vehicle travels in the time it takes for the driver to apply the breaks after realising they have to stop
When an electrical current flows through a resistor, why does it heat up?
There are collisions between the electrons and the ions in the resistor. This causes a transfer of kinetic energy into thermal energy which is released to the surroundings
What is absolute zero
Particles have no kinetic energy and do not move
(-273oc or 0 K)
Use your hand to show Flemings left hand rule, stating which finger represent field quantity
Thumb - force/direction of movement
Index finger - direction of Magnetic field
middle finger - direction of current
How does CMB show that the universe is expanding?
Cosmic microwave background radiation shows that the universe is expanding because the waves of energy have been stretched as the universe expanded to be classed as a microwave as it stretches out the wave
What is the difference between elastic and plastic behaviour?
Elastic - object recovers its original shape when the force causing it to extend is removed
Plastic - there is a permanent deformation to the shape of the object when forces are removed
Explain why the electrical heater of a kettle is placed at the bottom. (4)
- heat is maintly transferred by convection in liquids
- When a part of the liquid heats, it expands and becomes less dense causing it to rise
-The colder part is denser so it sinks to the bottom.
-this forms a convection current
Explain why kelvin is used instead of Celsius
Kelvin is directly proportional with the average speed or kinetic energy of particles. At 0K, particles do not move but at 0oc they do
How do loud speaker cones work? (6)
- coil is placed inside magnet
- alternating current in this coil produces magentic field
- The two fields interact and produce a force
- this movies the cone in different directions
- alternating current forces the cone to vibrate
- produces sound
State an equation linking change in wavelength, reference wavelength, recessional speed of galaxy and speed of light
change in wavelength/ reference wavelength = velocity of galaxy/ speed of light