Physics Flashcards
Find average acceleration, a =
a = Δv / Δt
For a body under constant acceleration, what is velocity: V =
V = Vo + at
For a body under constant acceleration, what is change in distance: ΔX =
Δx = V₀t + ½at²
Δx = Vavg • time
Δx = (½V₀+V)t
*for this one you can draw a line of initial and final velocity and find the middle value then multiply it by the time to find the distance
For a body under constant acceleration, find V without knowing time:
V² = V₀² + 2a (x-x₀)
For a body under constant acceleration, find average velocity;
→
V =
→
V = (½V₀+V)
Is weight a vector or scalar quantity? What is the formula for calculating weight?
Weight is a vector quantity
Weight = (mass) (gravity)
units: Kg·m/s² = newton
What are the Newton’s Three Laws of Motion?
1: A body in motion w/ constant velocity in a straight line path or at rest will remain that way unless a net for acts upon it.
2: Force = Mass x Acceleration = ma
3: To every force there is always an equal and opposite force
What are the formulas for the initial horizontal and vertical velocities of a projectile launched with speed v at an angle of theta to the horizontal?
Horizontal velocity = Vcosθ
Vertical velocity = Vsinθ
What does the total horizontal distance, x, traveled by a projectile equal?
X = V₀horizontal · time in air
What is the formula for gravitational force?
F = Gm₁m₂ / r²
If the distance between two objects doubled, by how much is the force of gravity increased or decreased?
The force would decrease by a factor of 4 (2^2)
T/F, A body in translational equalibrium has a net force moving it at a constant velocity?
False, a body in translational equilibrium has no net force acting on it.
If a lever arm is halved, by how much does the torque increase or decrease?
The torque would decrease by half
What is the formula for calculating torque?
τ = rFsinθ (r = the distance between force and axis of rotation)
When calculating torque, which rotation direction is considered positive and which negative?
-Counter Clockwise (to the left) is positive and Clockwise (to the right) is negative.
T/F For rotational equilibrium to occur, the sum of all torques acting on a body must be zero?
- True
What is translational motion?
-Translational motion is defined as motion in which the position of the object’s center of mass changes as a function of time
A block on an inclined plane, the gravitaional for point in which direction? What about the component of the force which contributes to the blocks motion down a 30° ramp?
1) Straight Down to the center of the earth
2) mg Sinθ from which you will be able to calculate acceleration down the incline.
*if there is friction it would be
(mg•Sinθ) - (Ff)
or
(mg•Sinθ) - (μk•Fn)
or
(mgSinθ) - (μk•mgCosθ)
A block on an inclined plane with angle of 30 to the horizontal, what is the normal force of the block?
mg Cosθ
*it points strait up with respect to the blocks horizontal plain which is slanted compared to the earths horizontal plane.
What is the formula for the force of static friction?
1) fk ≤ μsN
(μs = coefficient of static friction)
What is the formula for the force of kinetic friction?
1) fk = μkN
(μk = coefficient of kinetic friction)
What is the formula for centripetal acceleration (for a body in uniform circular motion)? a=
☛ a = ν²/r
(acceleration = velocity squared devided by radius)
(m²/s²)/(m) = m²/s²m = m/s²
What is the formula for centripetal force (for a body in uniform circular motion)? F=
☛ F = Kg · ac
(mass · centripetal acceleration)
(Kg · mv²/r) = the newton (Kg·m/s²)
T/F For a planet orbiting a star, the centripetal force is equal to the gravitational force?
☛ True
What is the formula for work? W =
◈ W=(Force · Distance) cosθ = Fdcosθ
What is the unit of work?
◈ The unit of work is the Joule (N · m)
What is the formula for power? P =
◈ P= W/t
(work / time)
(J/s) = (Kg·m²/s³)
What is the unit of power?
◈ The Watt (J/s) (N·m / s) (Ma · m / s) (Kg·m/s²·m/s) = (Kg·m²/s³)
What is the formula for kinetic energy? KE =
◈ KE = ½mass·velocity²
(½mv²) = (½)(Kg·m²/s²)
*remember that ½ is analogous to dividing by two (Kg·m²/s²)/2
What are the units of kinetic energy? KE =
◈ The units of KE are joules
(force · distance)
What is the formula for gravitational potential energy?
◈ U = (mass)(gravity)(hieght) = mgh
(Kg·m/s²·m) = Kg·m²/s²
also known as a Joule
What are the units of gravitational potential energy?
◈ The units of GPE are Joules : Kg·m²/s²
T/F, The total mechanical energy of a body is the sum of its kinetic and potential energies?
◈ True
Is total mechanical energy a constant if the only forces that act on a body are conservative ( E = K + U = constant)
◈Yes, E = K + U = constant
What is the change in energy of a system if only conservative forces act upon it?
◈If only conservative forces act on a body, then ΔE=0
What is the formula for momentum? p=
◈ p = (mass)(velocity) = mv
What is the formula for impulse j? j=
◈ j = (force)(time)
j = Ft
j = mv - mv₀ or change in momentum (Δp)
Is Kinetic energy conserved in a completely elastic collision?
◈Yes, kinetic energy is conserved in a completely elastic collision
T/F, Net external force must equal zero for conservation of momentum to occur?
◈True
What is the formula for the center of mass for two masses, m₁ and m₂, lying along the x-axis at points x₁ and x₂? X=
◈ X = (m₁x₁ + m₂x₂) / m₁+m₂
T/F, Momentum is not conserved in an inelastic collision?
◈False, momentum is conserved in both elastic and inelastic collisions.
What are the temperatures in Kelvin and Celsius for the following?
1. Absolute Zero 2. Freezing point of water 3. Boiling point of water
◈1. Absolute zero is 0°K and -273℃
◈2. Freezing (H₂O) is 273°K and O℃
◈3. Boiling (H₂O) is 373°K and 100℃
What is the formula for converting Kelvin to Celsius? Tc =
◈ subtract 273
Tc = Tk - 273
What is the formula for thermal expansion of a solid? ΔL =
◈ ΔL = αL·ΔT
alpha is the coefficient of linear expansion
What is the formula for volume thermal expansion of a liquid or a solid? ΔV =
◈ ΔV = βV·ΔT
beta is the coefficient of volume expansion
What type of heat transfer involves the direct transfer of energy from molecule through molecular collisions?
Conduction
What type of heat transfer involves the transfer of energy by electromagnetic waves?
Radiation
What type of heat transfer involves the physical motion of heated material?
Convection
What are the units of heat?
◈ The units of heat are the calorie, Btu, or Joule
What is the difference between a calorie and a Calorie?
◈ A Calorie is a nutritional term and is equal to 1000 calories.
What is the formula relating heat gained and temperature change? Q=
◈ Q = (mass)(specific heat)(ΔT) or mcΔT
What is heat of fusion?
◈ Heat of fusion is the amount of energy required for a phase change from solid to liquid
What is heat of vaporization?
◈ Heat of vaporization is the amount of energy required for a phase change from a liquid to gas.
What is the formula for heat gained or lost during a phase change? Q=
◈ Q=(mass)(heat of transformation) = mL
mL?
What is the SI unit of pressure?
◈ The SI unit of pressure is the Pascal
What is an isobaric process?
◈ An isobaric process is a process done at constant pressure
What is the formula for work (given an isobaric process)? W=
◈ P·ΔV
or (pressure)(Δvolume)
What is the formula for the First Law of Thermodynamics? ΔU=
◈ ΔU = (heat energy gained) - (work done by a system)
T/F, Heat flow out of a system is (+) and heat flow into a system is (-)
◈ False, heat flow out of a system is (-) and heat flow into a system is (+)
What is an adiabatic process?
◈ An adiabatic process is one in which no heat flows from the system to its surroundings (or vice versa)
What is the Second Law of Thermodynamics?
◈ The Second Law of Thermodynamics states that the entropy of a closed system will either increase or remain unchanged.
Does a totally reversible process increase the entropy of the universe? What about an irreversible process?
◈ A totally reversible process does not increase the entropy of the universe, but an irreversible process does.
What is the equation of density?
◈ ρ = (mass)/(volume)
Kg/m³ or g/cm³
What is the density of H20?
◈ ρwater = 1000 Kg/m³ or 1g/cm³
What is specific gravity?
◈ Specific gravity is the ratio of a substance’s density to the density of water.
What is the formula for calculating pressure?
◈ P = Force / Area = F / A
N/m² = (Kg·m/s²) / m² = Kg/s²m
What is the formula for absolute pressure in a liquid?
◈ P = (surface pressure) + (ρ)(gravity)(depth)
P= P₀ + ρgh
What is gauge pressure?
◈ Gauge pressure is the pressure in excess of atmospheric pressure
T/F, Pascal’s principle states that a change in pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and to the walls of the container
◈ True
What is the relationship between the areas and forces when a system is in equilibrium?
◈ F₁/A₁ = F₂/A₂
T/F, Both pistons move the same distance when a force is applied to one of them (refer to a picture with two pistons acting parallel to each other with one larger than another)
◈ False, the larger piston will move by a smaller distance
What is the formula for buoyant force? Fb =
◈ Fb = (density of the fluid)·(gravity)·(volume of the object immersed in the fluid)
Fb = ρgV
Given a pipe of varying cross sections, how do fluid velocity and cross-sectional area relate throughout the pipe?
◈ The smaller the cross sectional area, the greater the velocity.
T/F, According to Bernoulli’s Equation, as fluid velocity increases, absolute pressure decreases?
◈ True
What is viscosity?
Viscosity is the measure of the internal friction of a fluid.
Does the viscosity of a liquid generally increase or decrease as temperature rises?
An increase in temperature generally causes the viscosity of a liquid to decrease.
What is the formula for Young’s Modulus? Y=
Y = (F/A) / (ΔL/L) = Stress Force / Strain
T/F, Unlike charges attract and like charges repel?
True
What is the formula for Coulumb’s Law? F=
F = Kq₁q₂ / r² F = (constant)(charge₁)(charge₂) / (distance)²
If the distance between two charged objects is tripled, by how much does the elctrostatic force change?
The electric force would decrease by a factor of 9
If the distance between two charged objects is halved, by how much does the electrostatic force change?
The electrostatic force would increase by a factor of 4
What is the formula for an electric field at a distance (r) from a charge (q)? E=
E = k q/r²
In which direction will an electric field vector point around a positive charge?
The field vectors point away from a positive charge
In which direction will an electric field vector point around a negative charge?
The field vectors point toward a negative charge.
What is the formula for the force that a charge (q) experiences in an electric field (E)? F =
F = qE
What are the units of an electric field?
The units of an electric field are: Newtons/Coulomb or Volts/meter
What are the units of voltage?
The units of voltage are Volts or Joules/Coulomb
What is the formula for electric potential given a charge (q) at a distance of (r)? V =
V = K q/r
What is the potetial difference between two points on an equipotential line?
The potential difference is zero.
What is the formula for electrical potential energy? U =
U = qV
What happens to a dipole if it is placed in a uniform electric field?
The dipole will align with the electric field lines.
How much work is done on a charge if it is moved in a strait path between two equipotential points?
No net work is done.
What are the units of a magnetic field?
The units of a magnetic field are the Tesla. Sometimes the units given in Gauss: 1 Tesla = 10⁴ Gauss
What is the formula for the force on a moving charged particle in a magnetic field? F =
F = (charge)(velocity)(magnetic field)(sinθ) = qvBsinθ
What force will a stationary charged particle in a magnetic field experience?
A stationary particle will experience no force in a magnetic field
What force will a moving charge experience if it travels parallel or antiparallel to a magnetic field?
No force will be experienced if the charge moves parallel or antiparallel to the magnetic field.
What are the units of current?
The units of current are Amperes. 1A = 1 Coulomb / second