physics year 9 eoy exam Flashcards
what is the equation for speed
speed = distance/time
what is the equation for acceleration
acceleration = change in velocity/ time taken
how do you determine acceleration from a velocity-time graph
gradient of the line (rise over run)
how do you determine the distance travelled in a velocity time graph
area under the line
what is a vector and what is a scalar
a vector is a measurement of both magnitude and distance, a scalar only has magnitude
what is an insulator
current cannot flow through
what is a conductor
current can flow through
what is the equation for a force
f=ma
what is the equation for weight
w=mg
what forces would be acting on a block on a slope
normal reaction force upwards, gravitational force downwards, friction up the slope
what forces would be acting on a ship moving to the right
gravitational force down, up thrust up
thrust to the right, air/water resistance
what are some factors that could affect stopping distance (thinking and braking)
thinking:
- tiredness
- alcohol
- age
braking:
- bad tyre tread (no friction)
- bad breaks
- icy roads
how is stopping distance calculated
thinking distance + braking distance
how can you show that an object is charged?
it can pick up small bits of paper
how can you show that there are different types if charges
- charge two pieces of the same plastic
- suspend on of the rods so it can swing freely
- hold the other rod still and they should repel
- then charge to rods of different plastic and repeat
- they should attract
how would a rod and a cloth get charged
the cloth would transfer its electrons to the rod and becomes positive, the rod gains these electrons and becomes negative
what is one potential danger of electrostatic charge?
sparks causing explosions
what are the uses of electrostatic charges
- charged paint
-photocopiers
how is electrostatics used in photo copiers
- a rotating drum is given a positive charge
- a light is shined onto the paper to be copied and the reflection falls on the drum
-the drum is made of a special material that conducts in light; positive charge leaks away - negatively charged toner is spread on the drum
- the toner is only attracted to the charged area
- sheet of paper is passed over the drum
- the toner is transferred to the paper and heated to fuse it
what is a longitudinal wave?
a longitudinal wave oscillates along the direction of travel
what is a transverse wave?
a wave that oscillates perpendicular to the direction of travel
what are two examples of longitudinal waves
- sound waves
- Seismic P waves
what is the equation for wavespeed
wave-speed= frequency x wavelength
what is the equation for frequency (using the time period)
frequency = 1/time period
what are all the electromagnetic waves (in order of lowest frequency to highest)
non-ionising:
- radio
- micro
- infrared
- visible light
ionising:
- ultraviolet
- x-ray
- gamma
what are the uses and danger of radio waves
broadcasting and communication
no known dangers
what are the uses and danger of micro waves
cooking and satellite transmission
can cause burns, cataracts, or cancer
what are the uses and danger of infrared
heaters and night vision
skin burns
what are the uses and danger of visible light
optical fibres and photography
eye damage from bright lights
what are the uses and danger of ultraviolet waves
discos, counterfeit detection, tanning salons
skin cancer, damage to surface cells, blindness
what are the uses and danger of x-rays
imaging internal structures of objects and materials, studying atomic structure
damage to cells
what are the uses and danger of gamma rays
cancer treatment, observing the universe, sterilising medical equipment
cancer, cell mutation
what is the human hearing range?
20-20,000hz
what is the human hearing range?
20-20,000hz
what is the definition of a wave front
Points on a wave that oscillate in phase with each other
what are all the energy stores (8)
- thermal
- electrostatic
- kinetic
- chemical
- nuclear
- elastic
- gravitational
- magnetic
what are all the energy transfers
mechanical
radiation
electrical
thermal/heating
what is the principle of conservation of energy
energy cannot be created or destroyed, it can only be transferred
input energy= output energy
what is the equation for efficiency?
efficiency = useful energy output/energy input x100
energy transfer for electrical energy
chemical store of fuel –> thermal store of water (heat)
thermal store of water –> kinetic energy of turbines (mechanic)
kinetic store of turbines –> kinetic store of electricity generator (mechanical)
kinetic store of electricity generator –> electrical energy (electrically)
equation for density
density = mass/ volume
equation for pressure
pressure = force/ area
equation for pressure difference
pressure = height x gravitational field x density
properties of magnetically soft and magnetically hard materials + examples
soft:
- easy to magnetise and demagnetise
- iron
hard
- hard to magnetise and demagnetise
- steel
