Physics Flashcards
Why do heavy objects and light objects fall at the same rate?
Because every body attracts each other body at a rate proportional to its mass. In this way, a ball of twice the weight will have twice the force of gravity acting upon it!
What is the difference between special relativity and general relativity?
Special relativity ignores the effects of gravitation.
This means that since the speed of light is the same at every event and in every direction, all the light cones (of events in the universe) will be identical and point in the same direction
Everything must travel at or below the speed of light
What is the Newtonian theory of gravity?
Objects are attracted to each other with a force that depends on the distance between them
What are some key points on general relativity?
Space-time is not flat: it is curved or “warped”, by the distribution of mass and energy in it
Bodies (like earth) always follow straight lines in four-dimensional space time, but they nevertheless appear to move in curved paths in our three-dimensional space
The distance between New York and Cairo airports appear straight but is curved because the earth is curved
The shadow of an airplane on a hilly surface
The Doppler effect
Describes the change in wavelength of a wave as it travels closer (or farther) from/to an observer
What is the Chandrasekhar limit?
The mass at which a star is no longer able to support itself against its own gravity (and so it collapses)
Entropy
The amount of disorder in a system
What is Planck’s Constant?
Quantum value (h)
6.626 x 10 ^ -34 JS
The energy carried by a photon in relation to its frequency (color)
How can a black hole (in which nothing — including light — escape from) emit radiation (to prevent the breaking of the second law of thermodynamics)?
Because the radiation particles don’t come from inside the black hole… they come from the “empty” space just outside the event horizon!
Has to do with the creation/annihilation of particles and antiparticles where one is sucked in because of the tremendous gravity and the other one escapes
What is a virtual particle?
Unlike real particles they cannot be detected with a particle detector.
Their indirect effects, however, can be measured and predicted with high accuracy
Photoelectric Effect
Discovered by Einstein in 1905
Describes how light behaves like both a particle AND a wave
What is Newton’s second law?
Force = Mass * Acceleration
Or
Acceleration = Force / Mass
The larger something is, the more force is needed to change its direction
Applies to marketing
What is “The Scientific Method”?
An axiom is science that says you cannot prove a hypothesis through observation. You can only DISPROVE it
You can keep gathering data which will increasingly strengthen it, but only one contrary data point is needed to disprove it
Magnetic Dipole Moment
The tendency of a dipole magnet to rotate and align with an external magnetic field
A measure of how much it would interact with an external magnetic field of one existed
How are electric fields created?
By moving electric charges
