Paper 1 Flashcards
Equation for acceleration
acceleration = change in velocity / time taken
What is friction
A force that opposes motion
What is terminal velocity
The object moves at a steady speed in a constant direction because the resultant force acting on it is zero
1) object accelerates because it has weight
2) as speed increases so does drag
3) the forces balance and terminal velocity is reached
practical: investigate how extension varies with applied force for helical springs, metal wires and rubber bands
The spring constant of a spring can be found by carrying out an experiment.
The unloaded length of a spring is measured.
Slotted masses are added to the spring.
Record each stretching force in N and the corresponding length of the spring.
The extension is the new length minus the unloaded length.
Hookes law
Gradient of a force-extension graph is associated with Hooke’s law
(Spring constant)
Current in a resistor in domestic products
Resistance causes transfer of electrical energy to heat energy. Some components are designed to have a high resistance to make sure this happens, for example electrical heaters
Relationship between power, current and voltage
P = IV
A.C. and D.C.
Mains electricity is alternating current (oscillating voltage/current)
Direct current is supplied by a cell or battery (constant voltage/current)
Current in a series circuit
Is constant
Depends on the applied voltage
Graphs for resistors metal filament lamps and diodes
-
Voltage, current and resistance relationship
V = IR
If you increase resistance, the current
Decreases
For example adding more components
that light is part of a continuous electromagnetic spectrum that includes (in order)
radio, microwave, infrared, visible, ultraviolet, x-ray and gamma ray radiations
Wavelength and frequency in electromagnetic spectrum
decreasing wavelength and increasing frequency
Uses of radio waves
broadcasting and communications
Uses of microwaves
Cooking and satellite transmission
Uses of infrared radiation
Heaters and night vision equipment
Uses of visible light
Optical fibres and photography
Uses of ultraviolet light
Fluorescent lamps
Uses of x rays
observing the internal structure of objects and materials, including for medical applications
Excessive exposure of microwaves
Internal heating of body tissue
Excessive exposure of infrared
Skin burns
Excessive exposure of ultraviolet
Damage to surface cells and blindness
Excessive exposure of gamma rays
Cancer, mutation
What are light waves
Transverse waves that can be reflected and refracted
Law of reflection
the angle of incidence equals the angle of reflection
How do optical fibres work
Optical fibres made of plastic or glass consist of a central core surrounded by a cladding with a lower refractive index
Light signals passing through the core always hit the boundary at angles higher than c so the light is always totally internally reflected
This transmits information along them
What do optical fibres do
They are being used increasingly for telephone and broadband internet cables
Also for medical purposes to be able to see inside the body
What is a critical angle
when the angle of incidence is equal to the critical angle, the angle of refraction is 90 degrees
relationship between critical angle and refractive index
sin c = 1 / n
Principle of conservation of energy
It is not possible to create or destroy energy.
relationship between efficiency, useful energy output and total energy output:
efficiency = useful energy output / total energy output x 100
relationship between density, mass and volume
volume = mass / density
relationship between pressure, force and area
pressure = force / area
Molecules in a gas
have random motion and that they exert a force and
hence a pressure on the walls of a container
the Kelvin temperature of a gas is proportional to
average kinetic energy of its molecules
why does a nail exert more pressure on wood than on a hammer
- pressure is force divided by area
- the forces on wood and hammer are equal
- smaller area of nail is in contact with wood
Why is pressure inversely proportional to volume
As volume increase the space between the particles increases therefore frequency of collision decreases. Average force felt by container decreases so pressure decreases
Pressure and Kelvin temperature at constant volume.
As you heat the gas, the kinetic energy of the particles increases, and thus so does their average speed.
This means more collisions per second with the walls, and they exert a larger force on the wall.
This causes in the total pressure being exerted by the particles to rise
What is a magnetic field line
Magnets exert forces without touching
How to produce a uniform magnetic field
A uniform magnetic field is comprised of straight, parallel lines which are evenly spaced. Between two opposite charges on bar magnets, a uniform magnetic field is formed
Comet orbits
Around the sun
Highly elliptical
Planet orbits
Around the sun
Slightly elliptical
Moon orbits
Around planets
Circular
Uses of gamma rays
sterilising food and medical equipment.
energy transfers
mechanically, electrically, by heating, by radiation
