Physics Definitions and Equations Flashcards
Acceleration
How much an object’s speed changes in one second
Kinematics Equations (4)
Vf = Vo+at x = Vot+1/2at^2 Vf^2 = Vo^2+2ax x = 1/2t(Vo+Vf)
Angular Momentum (Extended object) Equation
L = Iw
Angular Momentum (Point object) Equation
L = mrv
Impulse- Momentum Theorem Equation
torque(time)= L
Change in angular momentum equals the net torque multiplied by the time the torque is applied
Displacement
How far an object ends up from its initial position
Average Velocity
Displacement divided by the time interval over which that displacement occurred
Instantaneous Velocity
How fast an object is moving at a specific moment in time
How to determine how far from the detector an object is located (Position-time graph)?
Look at the vertical axis of the position-time graph
How to determine how fast an object is moving (Position-time graph)?
Look at the steepness/slope of the position-time graph
How to determine which way the object is moving (Position-time graph)?
Look at which way the position-time graph is sloped
How to determine how fast an object is moving (Velocity-time graph)?
Look at the vertical axis of the velocity-time graph
How to determine which way the object is moving (Velocity-time graph)?
Look at whether the velocity-time graph is above or below the horizontal axis
How to determine how far an object travels (Velocity-time graph)?
Determine the area between the velocity-time graph and the horizontal axis
When an object is in free-fall…
Vertical acceleration is always 10 m/s
Horizontal acceleration is always zero
Angular Displacement (Theta)
The angle through which an object has rotated (radians)
Average Angular Velocity (w)
Angular displacement divided by the time interval over which that angular displacement occurred (rad/s)
Instantaneous Angular Velocity
How fast an object is rotating at a specific moment in time
Angular Acceleration (fishy a)
How much an object’s angular speed changes in one second (rad/s^2)
Difference between angular acceleration and centripetal acceleration?
Angular acceleration changes an object’s rotational speed.
Centripetal acceleration changes an object’s direction of motion.
Linear Displacement (Rotating object) Equation
x = r(theta)
Linear Speed (Rotating object) Equation
v = rw
Linear Acceleration (Rotating object) Equation
a = r(fishy a)
Torque Equation
torque = Fd
Rotational Inertia (I)
Resistance to angular acceleration
Rotational Inertia (Point particle) Equation
I = MR^2
Angular Acceleration Equation
fishy a = net torque / I
Mechanical energy is conserved when?
No net work done by external forces
Angular momentum is conserved when?
No net external torque acts
Momentum in a direction is conserved when?
No net external force acts in that direction
Momentum Equation
p = mv
(mass times velocity)
Units: Newton seconds
Impulse Equation
J = change in momentum
J = Ft
Units: Newton seconds
What is impulse in a force-time graph?
The area
Crest
High points on a wave
Trough
Low points on a wave
Amplitude (A)
The distance from the midpoint to the crest or trough
Wavelength (lambda)
The distance between identical parts of the wave
Frequency (f)
The number of waves to pass a position in one second
Units: Hertz (Hz)
Period (T)
The time for one wavelength to pass a position
Frequency Equation
f = 1/T
Period Equation
T = 1/f
Speed of a Wave Equations (2)
v = lambda(f) v = lambda/T
Transverse Wave
Motion of a material is at right angles to the direction in which the wave travels
Longitudinal Waves
A material vibrates parallel to the direction of the wave
Interference
Waves arrive at the same point at the same time
Constructive Interference
Crest of one wave overlaps the crest of another.
Result: Wave of increased amplitude
Destructive Interference
Crest of one wave overlaps the trough of another
Result: Wave of reduced amplitude
Superposition
Where the wave pulses overlap, the resulting displacement can be determined by adding the displacements of the two pulses
Beats
When two waves of slightly different frequency interfere. Beat frequency is the difference between the frequencies of the two waves
Doppler Effect
Change in frequency due to motion of the source.
Wave source approaches…waves with higher frequency
Wave source moves away…waves with a lower frequency
What does the pitch of a sound depend on?
Sound wave’s frequency
What does the loudness of a sound depend on?
Sound wave’s amplitude
What does the energy carried by a sound wave depend on?
Wave’s amplitude
Standing Wave
Wave that appears to stay in one place
Nodes
Stationary points on a standing wave
Antinodes
Positions on a standing waves with the largest amplitudes
Fundamental
The lowest frequency standing wave
How is wavelength measured on a standing wave?
Node to node
What is the fundamental frequency for a standing wave with identical boundaries?
v/2L
Harmonies exist in all multiples of the fundamental
What is the fundamental frequency for a standing wave with different boundaries?
v/4L
Harmonies exist only in odd multiples of the fundamental
Object in Equilibrium
The object moves in a straight line at constant speed. The net force is zero.
Force
Push or pull that acts on an object. It is always in the direction of acceleration.
Force Equation
F = ma
Units: Newtons
Equilibrium Force Equations
(up force)-(down force) = 0
(left force)-(right force) = 0
Mass
Tells how much material is contained in an object
Weight
Force of a planet acting on an object
Normal force
Force of a surface on an object in contact with that surface. It acts perpendicular to the surface.
What is the resultant force when two concurrent forces act perpendicular to one another?
Greater than if the forces acted in opposite directions, but less than if the forces acted in the same direction.
What is the horizontal and vertical component of a force when the angle of the diagonal force is measured from the horizontal?
Horizontal component is the magnitude of the force times cos(theta)
Vertical component is the magnitude of the force times sin(theta)
Force of Friction
Force of a surface on an object acting along the surface
Force of Friction Equation
Ff = uFn
Force of friction equals the coefficient of friction times the normal force
Difference between kinetic friction and static friction?
Kinetic friction is used when an object is moving. Static friction is used when an object is not moving.
Maximum coefficient of static friction is greater than the coefficient of kinetic friction.
Newton’s LUG
All massive objects attract each other with a gravitational force
Gravitational force (Fg) Equation
Fg = G (M1M2)/d^2
Gravitational Field (g) Equation
g = GM/d^2
Weight (aka gravitational mass) Equation
weight = mg
gravitational mass is equal to inertial mass
Inertial Mass Equation
F = ma
inertial mass is equal to gravitational mass
Component of the Object’s Weight (Parallel to incline) Equation
mg(sin(theta))
Component of the Object’s Weight (Perpendicular to incline) Equation
mg(cos(theta))
Newton’s Third Law
Force of object A on object B is equal to the force of object B on object A
Circular Motion Acceleration Equation
v^2/r directed towards the center of the circle
Work Equation
W = Fx
force multiplied by the distance an object moves parallel to that force
What is work in a force-displacement graph?
The area
What are the units for energy?
Joules (J)
Kinetic Energy Equation
KE = 1/2mv^2
gravitational Potential Energy Equation
PE = mgh
Mechanical Energy Equation
KE+PE = ME
Spring Potential Energy Equation
PE (spring) = 1/2kx^2
Rotational Kinetic Energy
KE (rotational) = 1/2Iw^2
Work- Energy Theorem Equation
W (external) = (KEf-KEi) + (PEf-PEi)
Force of a Spring Equation
F = kx
Units: Newton/meters
Power Equation
p = work/time
p = Force(velocity)
(amount of work done in one second)
What has the largest rotational inertia?
Hoop (I = mR^2)
Other rotational inertia equations contain a fraction before it
