Physics CH 3 & 4 Flashcards
Newton’s 1st law
An object at rest or moving at constant speed in a straight line will continue in that state until a net external force acts upon it
Newton’s 2nd law
Force is equal to mass times acceleration
F = m x a
Newton’s 3rd law
For every action, there is an equal and opposite reaction
Define mass
the amount of matter (stuff) in an object
Units of Force
Newton
Units of mass
Kg
Units of acceleration
m/s^2
Define velocity
A vector measurement of the rate and direction of motion
In other words, the displacement divided by the time it takes to make that distance
V = displacement/change in time
Define speed
A scalar measurement of distance over time
Speed = d/t
What is the difference between velocity and speed
Speed involves distance, velocity involves displacement (net change in the position of an object from start point to end point).
Speed is a scalar
Velocity is a vector
Define displacement
net change in position with respect to some specified beginning point or origin in a coordinate system.
Displacement can be positive, negative, or zero
What is a scalar
quantities that have magnitude only
ex: speed, distance, time, height, pressure, mass, age, energy, temperature, work, area, volume
What is a vector
quantities that have magnitude and direction
ex: velocity, weight, force, acceleration, displacement, electric field strength, torque, momentum
What is acceleration
Acceleration is a vector that describes how velocity changes with time
a = 🔺velocity/🔺time
What are the units of velocity
m/s
What are the 4 fundamental forces (strongest to weakest)
Strong nuclear force
Electromagnetic force
Weak nuclear foce
Gravitational force (more day to day CRNA stuff)
Define gravity
the universal attraction between all objects of mass
What is the formula for gravitational force
What is weight
the gravitational force exerted on an object by a much larger object such as the earth.
weight changes depending on location (earth vs moon) while mass does not change irrespective to its location
What do we know about weight in its relation to force
Weight = Force
W=m x g
Weight (W) = m (mass in kg) x g (gravity which is acceleration)
F = m x a
What is the constant gravitational (g) force equal
What is the unit of weight
Newton (N)
Since weight = force and the unit of force is N, then it is the same for weight
What is the British unit of force
the pound (lb)
what is the British formula for force
1 slug = ? kg
14.62kg
1lb = ? N
4.45N
what is the value for acceleration in the British constant ft/s^2
32.2ft/s^2
What is pressure?
pressure is the force per unit area
P= F/A
What are the units of pressure in the British system?
psi (pounds per square in) lb/in^2
What are the SI units of pressure
Pascal
Which is the pressure exerted by a force of 1N over 1 square meter of area
What are some examples of units of pressure
psi, pascal, atm, torr, bar, kilopascal
1atm = ? torr = ? mmHg = ? Pa
1atm = 760 torr = 760 mmHg = 101,325 Pa
1atm = ? bar
1.013 bar
1 bar = ? Pa = ? kPa
1bar = 100,000 Pa = 100 kPa
1kPa = ?Pa
1,000 Pa
1 psi = ? Pa
6,895 Pa
1 atm = ? psi
14.7 psi
What is the formula for atmospheric pressure
pressure is in Pascal
density (d=m/v)
height in meters (m)
What devices are affected by atmospheric pressure
manometers and bourdon gauges
What is gauge pressure
The pressure of a system about (or below) atmospheric pressure
What is the pressure formula for gauge pressure
Ptotal = Pgauge +Patmosphere
Define work
A force does work when it acts on an object and displaces the object in the direction of the force
So work is force times the displacement
Work (W) = F x d
SI unit of work
Joules (J)
1J = 1N x m
Centimeter-gram-second (cgs) system uses what unit for force
dyne
unit of cgs is Erg
1erg = 1dyn x cm = (g x cm^2)/s^2
1J = ? ft x lb
1J = 0.738 ft x lb
1 erg = ? J = ? ft x lb
1erg = 10^-7 J = 7.38 x 10^-8 ft x lb
What is kinetic energy
The energy a mass has by virtue of being in motion
KE is also called energy in motion
KE = J
So Si unit for KE is also J
What is the Work-Energy or Work-KE Theorem
The total work done on a system is equal to the system’s change in KE
What is the Volume of a cylinder
V is the product of area (TTr^2) times height
V= TTr^2 x h
height = displacement (d)
V=A x d or d=V/A
We know Work (W) = F x d, so if we fit this in, then
Work =F x V/A and Work = F/A x V, and F/A is pressure ( P=F/A)
1m^3 = ? L
1,000L
1J = ? Pa x m^3
1J= 1Pa x m^3
What are state functions
Mathematical functions that describe the “state” of a system
Ex: internal energy (U), volume, pressure, or temperature
State functions are INDEPENDENT of the path by which a system gets to a particular state
Isochoric
constant volume
isobaric
constant pressure
Reversible work means
when a change in volume (Vfinal-Vinital) is accomplished in an infinite number of steps and pressure is help constant for all the steps
only then can Work (W) = P - change in volume
Energy is defined as
the capacity to do work
What does the Law of conservation of energy state
energy is neither created nor destroyed but only converted to other kinds of energy
1 cal = ? J
4.184J
1kcal = ? cal
1,000 cal
What is potential energy
energy stored by virtue of position
KE is not destroyed, but converted to PE
Potential energy (PE) =
PE = m x g x h
m- mass in kg
g - acceleration dt gravity
h - height
Internal energy (U) is
the sum of all kinetic and potential energies of the particles comprising the system
The Zeroth Law of Thermodynamics states
Two objects (A & B) are found to be in thermal equilibrium that is, they are at the same temperature
The 1st Law of Thermodynamics states
Change in the internal energy (U) of a system is equal to the sum of the heat processes that cause energy to flow into/out of the system and the work done by/on the system
change U = Q + W(work)
Q= heat
Endothermic
Q > 0
Energy flows INTO the system, cools surroundings
Exothermic
Q < 0
Energy flow OUT of the system, heats surroundings
Expansion
Work (W) < 0
Work done BY THE SYSTEM on the surroundings
Compression
Work (W) > 0
Work done BY THE SURROUNDINGS on the system
The 2nd Law of Thermodynamics (entropy law) states
Heat spontaneously flows from a hot body to a cold body when the two bodies are brought into thermal contact
Entropy (a measure of randomness or disorder in a system) of the universe is constantly increasing
The 3rd Law of Thermodynamics states
It is not possible to lower the temperature of an object to absolute zero
The relationship of KE and Temperature can be expressed in what formula
T - temperature in kelvin
k - Boltzmann constant
k=1.38x10^-3 J/k
k - Boltzmann constant
k=1.38x10^-3 J/k
Heat capacity is defined as
the ratio between the amount of heat added to or take away from an object and the change in temperature of the object
Big “C”
C= Q/(change in Temperature)
SI units for heat capacity
J/K
Specific heat is defined as
The amount of heat added to or taken away from an object and the change in temperature of the object, but also accounting for the mass of the object
Little “c”
c= Q/m x (change in Temperature)
SI units for specific heat
J/kg x K
Little “c” is equal to what
4.18 J/g x K
Power is defined as
the rate of doing work or conversely, the rate of expending energy
Average power is calculated as
P = W(work)/t (time)
SI unit of power
Watt (W) in J/s
1 lb = ? kg
0.45 kg
1 kg = ? lb
2.2 lb
