Paper 2 Flashcards
use the relationship between weight, mass and gravitational field strength
Weight = mass x gravitational field strength
use the relationship between the moment of a force and its perpendicular distance from the pivot
moment = force × perpendicular distance from the pivot
the weight of a body acts through
its centre of gravity
What is the principle of moments
The principle of moments states that when the clockwise moments are equal to the anticlockwise moments a body will be in equilibrium
investigate how insulating materials can be charged by friction
Hold polythene rod and cloth next to up small pieces of paper one at a time, observe.
Now rub the rod with the cloth
Again hold close to small pieces of paper, observe.
Turn on a tap so a thin stream of water is flowing
Hold the rod about 1cm away from the water just below the nozzle, observe
Repeat with different material rods and cloths
explain how positive and negative electrostatic charges are produced on materials
If two materials are rubbed along each other one will gain electrons from the other. The one that has gained electrons has a negative charge as electrons are negatively charged
explain electrostatic phenomena in terms of the movement of electrons
the negatively charged balloon approaches the neutrally charged surface of the wall. the negative charges are repelled so only positive charge is left on the surface of the wall. negatively charged balloon and positively charged wall attract
potential dangers of electrostatic charges,
If the charge is very large, a spark to the earth may happen unexpectedly. Sparks like this can be dangerous, potentially igniting a fire. A build-up of static charge is a potential danger when refuelling aircraft or vehicles. Fuel running through the pipes can provide the friction needed to create a static charge.
know and use the relationship between the speed, frequency and wavelength of a wave:
wave speed = frequency × wavelength
use the relationship between frequency and time period
time period = 1 / frequency
investigate speed of sound in air using an oscilloscope
Connect two microphones to an oscilloscope
Place them about 2 m apart using a tape measure to measure the distance between them
Set up the oscilloscope so that it triggers when the first microphone detects a sound, and adjust the time base so that the sound arriving at both microphones can be seen on the screen
Make a large clap using the two wooden blocks next to the first microphone
Use the oscilloscope to determine the time at which the clap reaches each microphone and the time difference between them
Repeat this experiment for several distances
investigate speed of sound using wooden blocks
Use the trundle wheel to measure a distance of 100 m between two people
One of the people should have two wooden blocks, which they will bang together above their head to generate sound waves
The second person should have a stopwatch which they start when they see the first person banging the blocks together and stop when they hear the sound
This should be repeated several times and an average taken for the time travelled by the sound waves
Repeat this experiment for various distances
what is conduction?
Conduction is the transfer of thermal energy through a substance by the vibration of the atoms within the substance.
As the particles are heated, energy is transferred to their kinetic energy stores. The particles collide this neighbouring particles and transfer some of this energy to their kinetic energy stores, transferring energy through the solid in this way.
Metals are good conductors because they have free electrons that can move easily through the metal, making the transfer of energy happen faster.
what is convection?
Convection occurs in a liquid or gas. These expand when heated because the particles move faster and take up more volume – the particles remain the same size but become further apart. The hot liquid or gas is less dense, so it rises into colder areas. The denser, colder liquid or gas falls into the warm areas. In this way, convection currents are set up which transfer heat from place to place.
what is thermal radiation
Thermal radiation is the transfer of energy by infrared (IR) waves. These travel very quickly in straight lines
