Flashcards in Test 2 Deck (84)
Define Work? What is the formula for work?
Work is defined as a measurement of force displacing an object:
W = F x d (Work is equal to force x distance)
What is the SI unit of measurement for Work?
Other ways of expressing 1J?
1) 1J = N x m
2) 1J = kg x m^2/s^2
If you have 1kg mass you want to accelerate at 1m/s^2 over a distance of 1m. How much energy do you need?
Since W = F x d and F = m x a;
Then W = (m x a) x d
W = (1kg x 1m/s^2) x 1m = 1J or 1kg/m^2/s^2
How much work was done in Joules lifting a 100kg patient up to a distance of 0.02m straight up to place him onto the operating table?
Since W = F x d;
1st change weight into newtons because weight is acted upon by gravity which is newtons. So, 100kg = 981N, (1kg = 9.81N)
Now, w = 981 X .02 = 19.62J (rounding up gives you 20J or 2 x 10^1J
Define Kinetic Energy? what is the formula for it?
Kinetic Energy is described as energy of motion or the energy a mass has by virtue of being in motion.
KE = 1/2 mass x velocity (KE = 1/2kg x (m^2/s^2))
What is the SI unit of measurement for Kinetic Energy?
Joules or (kg/m^2/s^2); same as Force
What is the KE of a 55kg mass moving at 3.87 meters per second?
KE = 1/2m x velocity^2
KE = 0.5 x 55kg x (3.87m/s^2)
KE = 27.5kg x 14.97m^2/s^2
KE = 411.675J
What is the formula used to find the Work done by expanding gas?
W = P x ΔV
What is the formula used to find the volume of a cylinder?
V = A x h (Volume = area x height)
What is the SI units of measurement for volume?
How many Liters in 1 m^3?
How much work is done when 2.5L of gas expands to 3L against 600 Pa?
Since W = P x ΔV or W = P x (final volume - initial volume). Since 3L = .003m^3 and 2.5L = .0025m^3; then
W = 600 Pa x (3 x 10^-3m^3 - 2.5 x 10^-3m^3)
W = 600 Pa x (.0005)
W = 0.3 Pa x m^3
W = 0.30J (1J is equal to 1 Pa x m^3)
How much work is done when a ventilator increases the volume of air in the body by 500mL using 600Pa of pressure?
W = P x ΔV
W = 600Pa x .0005m^3 = .3J
A calorie is the amount of energy necessary to raise 1 gram of water 1 degree Celsius.
Whats the difference between a calorie and a Calorie?
Food Calories are actually kilocalories, written with a capitalized "C". So, one Calorie = 1 kilocalorie or 1000 calories.
How many Joules are in 1 calorie?
1kcal (1000 calories) = 4184J or
1J = .239 calories
How many Joules in a 2000kcal daily diet?
.239cal/1J = 2000kcal/xJoules. -->
.239x = 2000kcal (2,000,000 calories) --> x = 8,368,200J or 8.368 x 10^6J
If a 1500kg truck is traveling down the highway, how fast (v) must it be going to have the same energy as 2000kcal?
KE = 1/2m x v^2 --> V^2 = 2KE/m
v = sq. root of 2KE/m
v = sq. root of 2(8.37 x 10^6J)/1500kg
v = 106m/s or 237mph
Convert 106m/s to mph
1609m = 1 mile and 3600 secs in and hr
1690/106 = 15.17miles
3600secs/15.17miles = 237mph
Define Potential Energy? Give examples?
Energy that is stored by virtue of position (expressed in Joules). i.e.:
1) An airplane in the air
2) Chemical energy stored in food, glucose, or fat
Define Internal Energy? How is Internal Energy represented in an equation?
The sum of all the kinetic energy and potential energies of the particles in a system. It results from the state of the particles at the molecular level.
Represented by the letter "U"
The study of how energy is converted from one form to another, and how it flows into and out of a system. A system could be a test tube, a gas cylinder, a patient, etc.
What are the 4 Laws of Thermodynamics?
1) The Zeroth Law of Thermodynamics
2) The First Law of Thermodynamics
3) The Second Law of Thermodynamics
4) The Third Law of Thermodynamics
What is the Zeroth Law of Thermodynamics?
Says that if 2 systems are in a thermal equilibrium with a third system, then they are thermal equilibrium with each other.
Therefore, if the temperature of A = B, and B = C, then A =C.
What is the First Law of Thermodynamics?
The change in Internal Energy (U) of a system of heat (Q) flowing in or out of the system; and work (W) done by or on the system. (ΔU = Q - W) but is written as (ΔU = Q + W)
Why is the 1st Law of thermodynamics written as ΔU = Q - W instead of ΔU = Q + W?
Because heat and work can be added into or taken out of the system.
If Q > 0, the process is endothermic and heat flows into the system (+Q is used).
If Q < 0, the process is exothermic and heat flows into the system (-Q is used).
If W > 0, work done by system on surroundings aka expansion (-W is used).
If W < 0, work done by system on surroundings aka compression (-W is used).
What is the 2nd Law of Thermodynamics?
Says that entropy of the universe is constantly increasing. It does not become spontaneously more organized.
Give an example of the 2nd Law of Thermodynamics?
A mixture of oxygen and nitrous oxide in an anesthesia induction will not spontaneously separate and send only one gas to the patient.