# Shared Flashcard Set

## Details

Physics Formulas
Formulas for the MCAT
54
Physics
Not Applicable
04/24/2016

Term
 Resistance of a resistor =
Definition
 Resistance = pL/A   Resistance is given by the equation R=pL/A, where p is resistivity, L is the length of the resistor, and A is the cross-sectional area of the resistor.
Term
 Dot Product   A • B =
Definition
 [image]
Term
 Cross Product   u X v =
Definition
 [image] [image] [image]
Term
 Gravitational Force between two objects
Definition
 [image]where:   F is the force between the masses; G is the gravitational constant (6.674×10−11 N · (m/kg)2); m1 is the first mass; m2 is the second mass; r is the distance between the centers of the masses.
Term
 Newton's Laws
Definition
 First law: When viewed in an inertial reference frame, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force. Fnet = ma = 0   Second law: The vector sum of the forces F on an object is equal to the mass m of that object multiplied by the acceleration vector a of the object: Fnet = ma.   Third law:When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the first body.
Term
 Velcocity at time t when given initial velocity, aceleration and time
Definition
 V = V0 + at
Term
 Displacement when given initial velocity, aceleration, and time
Definition
 displacement: d = v0t + (at2)/2
Term
 Velocity when given intial velocity, aceleration, and position
Definition
 v2 = v02 + 2ax
Term
 Components of gravity on an inclined plane
Definition
 [image]
Term
 Centripetal Force
Definition
 The magnitude of the centripetal force on an object of mass m moving at tangential speed v along a path with radius of curvature r is: [image] where [image] is the centripetal acceleration.
Term
 Torque
Definition
 [image]               [image] where [image] is the torque vector and [image] is the magnitude of the torque,r is the position vector (a vector from the origin of the coordinate system defined to the point where the force is applied)F is the force vector,× denotes the cross product,θ is the angle between the force vector and the lever arm vector.
Term
 Kinetic Energy
Definition
 K = .5mv2
Term
 Gravitational potential energy
Definition
 U = mgh mass gravitational constant height
Term
 Elastic potential energy
Definition
 [image]   k = spring constant Δx = magnitude of displacement from equilibrium
Term
 Total Mechanical Energy
Definition
 E = U + K   Total = potential + kinetic
Term
 Conservation of mechaincal energyVS   Nonconservative work formula
Definition
 ΔE = ΔU + ΔK = 0   Wnonconservative = ΔE = ΔU + ΔK
Term
 Work Formula
Definition
 W = F • d = Fdcos(θ)   W = Work F = magnitude of the applied force d = magnitude of the displacement through the force applied θ = the angle between the applied force vector and the displacement vector
Term
 Pressure-Volume Work
Definition
 W = PΔV   Find the area under the curve with P on Y axis and V on the X.   Volume constant then no work.   Gas expands, W is positive Gas compresses, W is negative
Term
 Power Formula
Definition
 P = W/t = ΔE/t   Power equals work over time or the change in energy over time   Unit = J/sec
Term
 Work-Energy Theorem
Definition
 Wnet = ΔK = Kf - Ki
Term

Definition
 If a and b are distances from the fulcrum to points A and B and if force FA applied to A is the input force and FB exerted at B is the output, the ratio of the velocities of points A and B is given by a/b, so the ratio of the output force to the input force, or mechanical advantage, is given by [image] Because the power flow is constant, the torque TB and angular velocity ωB of the output gear must satisfy the relation [image] which yields [image]
Term
 Efficiency
Definition
Term
 Temperature conversions
Definition
 [image]
Term
 Linear Expansion Formula
Definition
 The change in the linear dimension can be estimated to be: [image] This equation works well as long as the linear-expansion coefficient does not change much over the change in temperature [image], and the fractional change in length is small [image]. If either of these conditions does not hold, the equation must be integrated
Term
 Volume Expansion Formula
Definition
 If we already know the expansion coefficient, then we can calculate the change in volume [image] where [image] is the fractional change in volume (e.g., 0.002) and [image] is the change in temperature (50 °C).
Term
 1st law of thermodynamics
Definition
 In a non-cyclic process, the change in the internal energy of a system is equal to net energy added as heat to the system minus thenet work done by the system, both being measured in mechanical units. Taking ΔU as a change in internal energy, one writes [image] where Q denotes the net quantity of heat supplied to the system by its surroundings and W denotes the net work done by the system. This sign convention is implicit in Clausius' statement of the law given above. It originated with the study of heat engines that produce useful work by consumption of heat
Term
 Heat gained or lost with temp change
Definition
 [image]
Term
 Heat gained or lost in phase change
Definition
 [image]
Term
 CHange in Enthropy
Definition
 ΔS = Qrev/t   S is change in entrhopy Q heat change in the process T = temp
Term
 Density
Definition
 Mathematically, density is defined as mass divided by volume: [image] where ρ is the density, m is the mass, and V is the volume.
Term
 Weight of a volume of fluid
Definition
 Fg = density * Volume * gravity constant   For fluids
Term
 Specific Gravity
Definition
 Specific gravity is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume. It can be shown that true specific gravity can be computed from different properties: [image]
Term
 Pressure
Definition
 Pressure = Force/Area
Term
 Absolute Pressue
Definition
 The total pressure that is exerted on an object that is submerged in a fluid   Pressure = surface pressure + density*gravity acceleration*depth P = P0 +ρgz
Term
 Gauge Pressure
Definition
 Pgauge = P-Patm = (p0+ρgz)-patm   ρ  = density g = acceleration due to gravity z=depth
Term
 Pascal's Principle
Definition
 Seen in pistons P = F1/A1 = F2/A2 F2=F1(A2/A1)
Term
 Archimedes Principle Buoyancy
Definition
 Fbuoy = ρfluid*Vfluid displace*g = ρfluid*Vsubmerged*g
Term

# Poiseuille equation

Flow through a pipe

Definition
 [image] where: [image] is the pressure loss[image] is the length of pipe[image] is the dynamic viscosity[image] is the volumetric flow rate[image] is the radius[image] is the velocity
Term

# Critical Velocity

Definition
 [image]  Nr is a constant η = viscosity density diameter
Term
 Continuity Equation
Definition
 Q = Flow rate = v1A1 = v2A2
Term
 bernoulli's equation
Definition
 [image]
Term

# Coulomb's law

Definition
 In its scalar form the law is: [image] , where ke is Coulomb's constant (ke = 8.99×109 N m2 C−2), q1 and q2are the signed magnitudes of the charges, the scalar r is the distance between the charges.
Term
 Electric Field
Definition
 E = Fe/q = kQ/r2
Term
 Electrical Potential Energy
Definition
 [image],

where [image] is Coulomb's constant, r is the distance between the point charges q & Q, and q & Q are the signed values of the charges

Term
 Electrical Potential   From Potential Energy vs From Source Energy
Definition
 V = U/q   vs   V= kQ/r
Term
 Voltage   ΔV =
Definition
 ΔV = Vb - Va = Wab/q
Term
 The potential of an electric dipole
Definition
 V = (kqd)/r2 * cosθ
Term
 Dipole Moment
Definition
 p = qd
Term
 Electric field on the perpendicular bisector of a dipole
Definition
 E = 1/(4∏ε0) * p/r3
Term
 Torque on a dipole in an electric field
Definition
 τ = pEsin(θ)
Term
 Magnetic field from a    Straight Wire vs Loop of wire
Definition
 B = (μ0I)/(2πr)   vs   B = (μ0I)/(2r)
Term
 Magnetic Force on a...   Moving point charge vs Current-carrying wire
Definition
 Fb = qvB*sin(θ) vs Fb = ILB*sin(θ)
Term
 Current
Definition
 I = Q/Δt
Term
 Ohm's Law
Definition
 I = V/R
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