Physics June P1 Flashcards
Free fall
the motion of an object under the influence of gravity only
projectile
n object launched with an initial velocity and upon which the only force action is the force of gravity
when is no work done on an object
No displacement
force acts perpendicular to the displacement
work energy theorem
the net work done on an objects equal to the change in the object’s kinetic energy
power
the rate at which work is done (scalar quantity measured in watts)
when do you use the principle of conservation of Emech
when there is no friction
conservative force
a force for which the work done in moving an object between two points is independent of the path taken
non conservative force
a force for which the work done in moving an object between two points depends on the path taken
gravitation potential energy
energy an object has because of its position in the gravitational field relative to a reference point
kinetic E
Energy an object has as a result of its motion
mechanical E
sum of an object’s kinetic and potential E
momentum
product of objects mass and velocity (p=mv)
Newton’s 2nd law of motion in terms of momentum
the net force acting on an object is equal to the rate of change of momentum of the object in the direction of the net force
impulse
product of net force and time
isolated system
system on which the net external force is zero
elastic collision
total kinetic E is conserved
doppler effect
the apparent change in frequency of a sound detected by a listener as a result of the relative motion between the source of sound and the listener
frequency
number of wave pulses per second
period
time taken for one complete wave pulse
wavelength
distance between two successive points in phase
doppler effect uses
detect a foetal heartbeat
measure the rate of blood flow
red shift
when a star moves away from the earth, the light waves behind the star increase, causing a shift of the light towards the red end of the spectrum
weight
gravitational force exerted by the earth on an object or near its surface
newton law of universal gravitation
each body in the universe attracts every other body with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres
potential difference
energy transferred per unit charge flowing between two points through a conductor (V=W/Q)
emf
energy provided by a battery per unit charge flowing through the battery
current strength
rate of flow of charge (I=Q/t)
resistance
ratio between the pot. diff. across a resistor and the current in the resistor (R=V/I)
one ohm
one volt per ampere
ohm’s law
pot. diff. across a conductor is directly proportional to the current in the conductor at constant temp
series vs parallel
series divides V
parallel divides I
electric field
region of space in which an electric charge experiences a force
electric field at a point
the electrostatic force experienced per unit positive point charge placed at that point
principle of conservation of charge
the net charge of an isolated system remains constant during any physical process
photoelectric effect
process whereby electrons are ejected from a metal surface when light of suitable frequency is incident on that surface
photon
an energy packet of light
Threshold frequency
minimum frequency of light needed to emit electrons from a certain metal surface
threshold wavelength
maximum wavelength of light needed to emit electrons from a certain metal surface
work function
the minimum energy that an electron of a particular metal needs to be emitted from the metal surface
what nature of light does the photoelectric effect prove?
that light has a particle nature
RMS voltage
the potential difference in an AC circuit that dissipates the same amount of energy as a DC circuit
RMS current
the current in an AC circuit that dissipates the same amount of energy as a DC circuit
explain electromagnetic induction by a generator
the armature causes a change in magnetic flux linked to the coil and this induce a current in the coil
coulombs law
the magnitude of the electrostatic force of attraction or repulsion exerted by one point charge on another point charge is directly proportional to the magnitude of the product of their charges and inversely proportional to the square of the distance between their centres
principle of conservation of charge
the net charge of an isolated system remains constant during any physical process
