Physics 2 Flashcards
What is the difference between scalar and vector quantities?
Scalar has only magnitude; vector has magnitude and direction.
What is the equation for weight?
Weight = mass × gravitational field strength
What is a resultant force?
The overall force when multiple forces act on an object
What happens when work is done on an object?
Energy is transferred
What does Hooke’s Law state?
Force = spring constant × extension (F = k × e)
What is the limit of proportionality?
The point beyond which extension is no longer proportional to force
What is a moment?
The turning effect of a force = force × distance from pivot
How can you increase the moment of a force?
Increase the force or distance from the pivot
Why does pressure in a fluid increase with depth?
Because there’s more weight of fluid above
What causes atmospheric pressure to decrease with altitude?
Fewer air molecules higher up
What is the difference between distance and displacement?
Distance is scalar; displacement is vector
What is the difference between speed and velocity?
Speed is scalar; velocity is vector
What does the area under a velocity-time graph represent?
Distance travelled
What does the gradient of a velocity-time graph show?
Acceleration
State Newton’s First Law.
An object will remain at rest or in constant motion unless acted on by a resultant force
State Newton’s Second Law.
Force = mass × acceleration
State Newton’s Third Law.
For every action there is an equal and opposite reaction
What affects a vehicle’s braking distance?
Speed, road conditions, tyre/brake condition
What is momentum?
Momentum = mass × velocity
What does conservation of momentum mean?
Total momentum before = total momentum after (in a closed system)
How do crumple zones and seatbelts reduce injury?
They increase the time over which momentum changes, reducing force
What are transverse waves?
Waves with oscillations perpendicular to the direction of energy transfer
What are longitudinal waves?
Waves with oscillations parallel to the direction of energy transfer
What is the difference between frequency and period?
Frequency = number of waves per second; period = time for one wave
What is the relationship between wave speed, frequency and wavelength?
Wave speed = frequency × wavelength
What is the law of reflection?
Angle of incidence = angle of reflection
What causes refraction?
Wave speed changes when entering a different medium
Name the electromagnetic spectrum in order.
Radio, Microwave, Infrared, Visible, Ultraviolet, X-ray, Gamma
Which EM waves are ionising?
Ultraviolet, X-rays, Gamma rays
What is infrared radiation used for?
Heating and thermal imaging
What is UV radiation used for?
Fluorescent lamps, security marking, sunbeds
What is the danger of X-rays and Gamma rays?
Can cause mutations and cancer
How do sound waves travel?
As longitudinal waves through solids, liquids, or gases
What happens to sound when it enters a denser medium?
It speeds up
What does the frequency of a sound wave affect?
The pitch of the sound
What is ultrasound used for?
Imaging (e.g. foetal scans) and detecting flaws in materials
What are seismic waves?
Waves that travel through the Earth from earthquakes
What is the difference between P-waves and S-waves?
P-waves are longitudinal and travel through solids and liquids; S-waves are transverse and only travel through solids
What do magnetic field lines show?
The direction and strength of a magnetic field
What is the difference between permanent and induced magnets?
Permanent magnets always produce a field; induced magnets are temporary
What does the motor effect describe?
A force experienced by a current-carrying wire in a magnetic field
What factors affect the force in the motor effect?
Strength of magnetic field, current, and length of wire
What is an electric motor?
A device that uses the motor effect to produce rotation
How can a potential difference be induced?
By moving a conductor in a magnetic field or changing the magnetic field
What is the difference between an alternator and a dynamo?
Alternator produces AC; dynamo produces DC
How do microphones work?
Sound waves move a diaphragm that induces a current in a coil
How do loudspeakers work?
AC current causes coil to move in a magnetic field, producing sound
What does a transformer do?
Changes the potential difference of an alternating current
What is the role of a step-up transformer?
Increases voltage, decreases current
Why is a step-up transformer used in the National Grid?
To reduce energy loss from heating
What does a step-down transformer do?
Decreases voltage for safe use in homes
Why does the National Grid use high voltage?
To reduce current and energy loss by heating
What objects make up the solar system?
Sun, planets, dwarf planets, moons, comets, asteroids
What force keeps planets in orbit around the Sun?
Gravitational force
What is the order of star formation?
Nebula → Protostar → Main sequence → Red giant/supergiant → White dwarf/supernova
What is a protostar?
A collapsing cloud of gas and dust where fusion is starting
What is a main sequence star?
A stable star where gravity is balanced by fusion pressure
What happens to a sun-sized star after red giant stage?
It becomes a white dwarf, then a black dwarf
What is a supernova?
A huge explosion from a red supergiant
What can a supernova form?
A neutron star or a black hole
How are elements heavier than iron formed?
In supernovae
What does red-shift tell us?
Distant galaxies are moving away – universe is expanding
What does more red-shift mean?
The galaxy is moving away faster
What is Cosmic Microwave Background Radiation?
Low energy radiation left over from the Big Bang
What does CMBR support?
The Big Bang Theory
Why does orbital speed increase in lower orbits?
Stronger gravitational force
What type of orbit do communication satellites use?
Geostationary orbit (24-hour period)
What type of orbit do imaging satellites use?
Low polar orbit (frequent passes over Earth)
What is a black hole?
A very dense object with gravity so strong not even light can escape
