Physics Flashcards
These are physical quantities that have magnitude only and can be handled like ordinary real numbers.
Ex: Mass Time Temperature Energy Speed Distance Work Power
Scalar Quantities
Physical quantities with magnitude and a specified direction in space. Denoted by an uppercase letter in boldface, like A, to distinguish them from scalar quantities.
Ex. Displacement Velocity Acceleration force Momentum Impulse
Vector Quantities
The scalar corresponding to a vector, denoted by |V| or simply V.
P.S. This is never a negative number. The zero vector has undefined direction
Magnitude of a vector
V = W if and only if |v| = |w| with V and W along the same direction.
Vector Equality
A vector that has the same magnitude as the given vector but points in the opposite direction
|V| = |-V|
Negative of a vector
The individual projections of a vector onto the x- and y-axes ; given by Vx and Vy, respectively
Vx = |V|cos(angle) Vy = |V|sin(angle)
Components of a Vector
Sin 0 degrees = cos 90 degrees = 0
Sin 90 degrees = cos 0 = 1
Sin 45 degrees = cos 45 = Square root of 2 over 2
Sin 30 degrees = cos 60 degrees = 1/2
Sin 60 degrees = cos 30 degrees = Square root 3 over 2
Trigonometric ratios of some angles
V =
θ = tan⁻¹|Vₓ/Vᵧ|
|V| = √Vₓ²+vᵧ²
component form of a vector
Study of motion
kinematics
length of the line or curve following the object’s path, scalar, SI unit: meter (m)
Distance
Change in object’s position, vector pointing from object’s initial position to final position, SI unit: meter (m).
in one direction
∆x = Xf - Xi
Displacement
distance traveled by an object over the time elapsed, scalar, SI unit; meters per second (m/s)
average speed = d/t
Average speed
Speed of an object at an instant of time, scalar, SI unit: m/s
Instantaneous speed
displacement of the object over the time elapsed , vector, SI unit of magnitude: m/s.
In one dimension, the average velocity of an object is
ave v = ∆x/ t
in two dimensions
v ave = <∆x/t, ∆y/t>
Average velocity
velocity of an object at an instant of time, vector, when velocity changes uniformly then
v ave = (Vf + Vi) / 2
instantaneous velocity
when the velocity of an object is _______, then instantaneous velocity is equal to average velocity. If speed is _____, then instantaneous speed is equal to average speed
Constant
Change in an object’s velocity, not zero when object speeds up, slows down, changes direction. SI unit: Meters per second squared (m/s^2)
Acceleration
When the acceleration of an object is ______, it travels at a constant speed along a straight line
Zero
Motion of an object with no acceleration, in one dimension:
v = ∆x/t
Uniform motion
motion of an object with constant, non-zero acceleration along a straight line
a = (Vf - Vi)/t Vave = (Vf - Vi)/2 = ∆x/t
Vf = Vi +at Vf^2 = Vi^2 + 2a∆x ∆x = ((Vf + Vi)/ 2) t ∆x = Vit+1/2at^2
PS. the appropriate equation is the one that has 3 of the given and the variable that is asked for
uniformly accelerated motion
if the _____ an object’s acceleration and that of its velocity are the same, then the speed of the object is increasing. If the _____ of an object’s acceleration and that of it’s velocity are opposite, then the speed of he object is decreasing
direction
The instantaneous speed of an object at a ___________ is zero
turning point
State of an object’s motion when the acceleration is the acceleration due to gravity only
examples:
coin dropped downwards
baseball that was batted and is flying in the air as a result
Free fall
Acceleration that has a magnitude of g = 9.8 m/s^2 and is directed vertically downwards. all objects regardless of mass accelerate at this rate near the surface of the earth. The acceleration on the moon is 1.6 m/s^2
acceleration due to gravity
v = Vi -gt v^2 = Vi^2 - 2g∆y 2∆y = (v + Vi)t ∆y = Vit - 1/2gt^2
Equations governing free fall
motion of an object that is going around in a circle at a constant speed
Uniform circular motion
acceleration of an object in uniform circular motion, always points towards the center of the circle
Ac = V^2 / r
V = (2 pi r)/T T = time / # of revolutions
Centripetal acceleration in uniform circular motion
the resistance of an object to a change in its state of motion
inertia
motion of an object that does not accelerate; an object is in a constant sate of motion is either a motion with constant speed along a straight line or at rest
constant state of motion
the amount of matter in a given object (SI unit is kg)
mass
a push and pull; a vector
force
The SI unit for force; represented by the symbol N; 1 N= 1 kg m/s^2
Newton
the force of gravity exerted by a planet (or other similar heavenly bodies) on an object; it varies with location in the universe
weight
also called fundamental forces, only four are known to science:
gravitational force acts on masses, has infinite range, the strength is very weak, always attractive and universal
Electromagnetic force acts on charges , has infinite range, with strong strength, may be attractive or repulsive
Weak nuclear force, acts on ‘flavor’ charges, has very short range, weak strength, and is responsible fr some forms of radioactivity
Strong nuclear force, acts on ‘color’ charges, has short range, but a very strong strength, and is responsible for holding the nucleus together
Non-contact Forces
forces which require contact between the interacting object, derived from fundamental forces
example: normal force tension friction air resistance
contact forces
force exerted by a surface on objects it is in contact with; always perpendicular to the surface
normal force
force exerted by a tout string or rope
tension
force exerted by a rough surface on object rubbing against them
friction
retarding force exerted by air on objects moving through it
air resistance
States that an object in a constant state of motion will remain in this state unless it is acted upon by a net external force.
If an object is at rest, it will remain at rest unless a force acts on it. An object travelling at a constant velocity will not change this velocity unless a force acts on it
First law of motion / the law of inertia
States that the net force acting on an object is equal to the object’s mass times its acceleration.
F = ma
f = 0 then a = 0 (this is just the first law)
Second law of motion or the law of acceleration
states that for every action there is an equal and opposite reaction
Fab = - Fba
Third law of motion/ law of action and reaction
The magnitude of the earth’s gravitational pull on an object
w = mg
weight
the force that keeps an object in uniform circular motion, always points toward the center of the object’s orbit
Fc = m v^2/r
Centripetal force
An object’s capacity to do work, scalar. SI unit: 1 joule = 1 J = 1 kg m^2/s^2
energy
“the energy lost to a system is equal to the energy gained by its surrounding”
‘The energy of an isolated system remains constant in time’
The law of conservation of energy
The energy due to the configuration and motion of an object’s molecules or atoms
forms:
thermal energy
chemical energy
nuclear energy
internal energy
the energy due to the motion or vibration of an object’s molecules; the energy of an object stored in heat
thermal energy
the energy of the chemical bonds making up matter
chemical energy
the energy that bind an atom’s nucleus together
nuclear energy
the energy of an object manifested in its state of motion
KE = 1/2mv^2
Kinetic energy
