external revision Flashcards
horizontal and vertical components are _____ of eachother
independent
define the term normal force
the force acting along an imaginary line drawn perpendicular to the surface
describe uniform circular motion
the motion of an object travelling at a constant speed in a circle. Force acting on an object is perpendicular to the velocity of the object (velocity is tangential to the motion of the object)
define centripetal acceleration and force
the acceleration and the force experienced by any object moving in a circular path directed towards the centre of motion.
recall newton’s law of universal gravitation
the force of attraction between each pair of point particle is directly proportional to the product of their masses and inversely proportional to the square of the distance between them
define the term gravitational fields
is the region of space surrounding a body in which another body experiences a force of gravitational attraction
recall kepler’s law of planetary motion
- First law of planetary motion states that all planets move about the Sun in elliptical orbits, having the Sun as one of their foci
- Second law of planetary motion (law of areas) states that a radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time
- Third law of planetary motion (law of periods) states that the square of the sidereal period of a planet is directly proportional the cube of its mean distance from the Sun T^2/r^3
define coulomb’s law
- describes the force exerted by electrostatically charged objects on other electrostatically charged objects
- that like electric charges repel and opposite electrical charges attract
define the terms electric fields, electric field strength and electrical potential energy
- Electric field is a region of space near an electrically charged particle or object within which a force would be exerted on other electrically charged particles or objects
- Electric field strength is the intensity of an electric field at a particular location (NC-1)
- Electrical potential energy is the capacity of electric charge carriers to do work due to their position in an electric field (J)
define the term magnetic field
is a region of space where a magnetic force is experienced
explain the right hand palm rule
palm - force
fingers - field direction
thumb - current
explain the right hand grip rule
fingers - field/current direction
thumb - north pole (magnetic field direction/current)
define magnetic flux
a measurement of the total magnetic field that passes through a given area
define electromagnetic induction
the production of an electromotive force (EMF) or voltage across an electrical conductor due to its dynamic interaction with a magnetic field
define electromotive force
(EMF) is the difference in potential that tends to give rise to an electric current
define faraday’s law
states that when the magnetic flux linking a circuit changes, an electromotive force is induced in the circuit proportional to the rate of change of the flux linkage
define lenz’s law
states that the direction of an induced electric current is such that it produces a current whose magnetic field opposes the change in the circuit or the magnetic field that produces it
describe the process of inducing an EMF across a moving conductor in a magnetic field
change any of the variables in the formula eg. the field strength, the area, the angle or the number of turns
explain how transformers work in terms of Faraday’s Law and electromagnetic induction
- work through mutual induction - the production of an EMF
- transfers an alternating current from one circuit to another, usually with an increase or decrease in voltage
define and explain electromagnetic radiation in terms of electric fields and magnetic fields.
refers to the waves of the electromagnetic field, propagating through space, carrying electromagnetic radiant energy (radio, microwave, x-ray)
describe an example of natural phenomena that cannot be explained by Newtonian physics, such as the presence of muons in the atmosphere
- the average life span of a muon is 2.2 microseconds and then decays into an electron and two neutrinos
- This confirmed Einstein’s theory of relativity
○ To the observers, distance from mountaintop to sea level - 1910 (scientists’ frame of reference)
○ For the muon, the distance was 183m (muon’s frame of reference)
▪ Due to length contraction for objects travelling at relativistic speeds
○ Muon’s lifetime changed from 2.2 microseconds to 23 microseconds
▪ Due to time dilation for objects travelling at relativistic speeds`
define the terms frame of reference and inertial frame of reference
is a non-accelerating frame of reference in which Newton’s laws of motion hold
recall the two postulates of special relativity
- The laws of physics are the same in all inertial frames of reference
- The speed of light has a constant value for all observers, regardless of their motion or the motion of the source
explain the concept of simultaneity
relation between two events assumed to be happening at the same time in a frame of reference
- Relativity of simultaneity states that events that are simultaneous in one frame of reference are not necessarily simultaneous in another frame of reference, even if both frames are inertial
e.g. if two school bells ring, and you are positioned directly between them, they will be heard simultaneously. However, if you are positioned closer to one of the bells, you will hear one before the other, meaning the event is not simultaneous