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Physics Paper 2, Newtons Law, RP: stretched spring, Work done, magnestism,…
Physics Paper 2
RP: investigate infrared radiation
Shiny silver
Matt White
Matt Black
No covering
Dull (matt) dark surfaces are better emitters of infrared radiation than shiny light surfaces.
WAVES
Longitudinal waves:
when particles in the wave are close together this is called compression. when particles in the wave are far apart this is called rarefaction. SOUND WAVES
speed of wave (m/s) = frequency of wave (Hz) x wavelength (m)
RP:
Set up ripple tank to produce low frequency waves.
Adjust height of lamp s waves are visible on card.
Ruler ar right angle to waves.
Measure length of five waves on card
Count the number of waves passing mid-point of card in 10s.
Calculate: wavelength, frequency, wave speed.
Electromagnetic waves are
transverse waves
that transfer energy from the wave source to an absorber;
gamma rays, X-ray, ultraviolet, infrared, microwave, radio.
LIGHT WAVES
RP: Investigate infrared radiation (Temp change)
Force and Extension
Scalars:
measure with magnitude (size); time, mass, temperature, speed, direction.
Vectors: measure both magnitude and direction; forces, displacement, velocity, acceleration, momentum.
CONTACT FORCE:
Reaction force (normal contact): object at rest on a surface.
Tension: object that is being stretched.
Friction: two objects colliding past each other.
Air resistance: object moving through the air.
NON-CONTACT FORCE:
Gravitational force: masses are attracted towards each other by gravitational force.
Weight (N) = Mass (kg) x Gravitational field strength (N/kg)
Magnetic force: magnetic aterial in a magnetic field.
Electrostatic force: any charged particle in an electric field.
Resultant Forces:
number of forces acting on an object may be replaced by a single force that has the same effect as all the original forces acting together.
Stopping distance = thinking distance + braking distance
Stopping distance
of a car is the minimum distance that a car can safely stop in.
Thinking distance
is the distance travelled by the vehicle in the time it takes for the driver to react and start to apply the brakes; eg. alcohol, drugs, distractions, mobile phone, speed, tiredness.
Braking distance
is the distance travelled by the vehicle after the brakes are applied until it comes to a complete stop, as a result of the braking force.
Hooke's Law: force applied are directly proportional to the extension
Newtons Law
1st LAW:
the object is stationary, the object remains stationary.
the object is moving, the object continues to move at the same speed and in the same direction. object moves at the same velocity.
2nd LAW:
the acceleration of an object is proportional to the resultant force acting on the object, and inversely proportional to the mass of an object.
Force (N) = Mass (kg) x Acceleration (m/s2)
3rd LAW:
Whenever two objects interact, the forces they exert on each other are equal in size and opposite in direction.
RP: Investigating how force affects acceleration. Investigate the effect of varying the force on the acceleration of a object of constant mass.
RP: stretched spring
Measure original spring length. Mass (100g) added each time on spring. Measure the new length of the spring.
Independent variable: what you change.
Dependent variable: what you measure.
Control variable is what you need to keep the same.
Work done
force moves an object from one position to another, energy must be transferred from one energy store to another.
work done is the energy transferred when a force moves an object through a distance.
magnestism
Magents:
two north poles or two south poles repel each other but a south pole and a north pole attract each other.
Magnetic fields:
region around a magnet where a force acts on another magnet or on a magnetic material.
The direction of a magnetic field is always drawn from north to south. Lines DO NOT cross.
Magnetic material
Iron (including some steels)
Cobalt
Nickel
They can all be magnetised, though iron loses its magnetism as soon as the magnetising force is removed.
Types
An
induced magnet
is a material that becomes a magnet when it is placed in a magnetic field. When removed from the magnetic field it loses most or all of its magnetism quickly
Permanent magnets
are made from nickel, cobalt and some types of steel. The force between a magnet and a magnetic material is always attractive.
electromagnetism
Electricity and magnetism are very closely connected. By combining the two we can create much more powerful magnets or electromagnets.
increase
Increase the current passing through the wire
Making the wire into a coil
Increasing the number of coils in the wire
Putting an iron core in the centre of the coil
EM Spectrum:
Radio
(signals and sounds),
Microwaves
(wifi and heat),
Infrared
(heat),
Visible
(light, mirrors),
Ultraviolet
(UV lamp, tanning beds),
X-ray
(bone images),
Gamma rays
(medical purposes).