Kinetic Theory Flashcards
Kinetic Theory
Atomic description of gases as well as liquids and solids. It models the properties of matter in terms of continuous random motion of the molecules
The temperature of gases is proportional to the average _______________ kinetic energy of molecules.
translational (this means all points of a moving body move uniformly in the same direction). If an object is undergoing translatory motion, we can note that there is no change in the object’s orientation
There is a very large number N of molecules, _________
all identical and each having the mass m.
The molecules obey ___________ and are in continuous motion, which is _________
Newton´s laws; Random and isotropic (the same in all directions)
How to derive ideal gas law and connection between microscopic quantities? (Like energy of a typical molecule or temperature)
Analyze sample of gas in a rigid container
When you´re analyzing a sample of gas in a rigid container, what assumptions do you make of it?
-Molecules are smaller than average distance between them
-Therefore total volume is much less than that of the container
-Therefore the Van der Waals constant is negligible. (Is necessary for comparison of volume of gas molcules vs volume of a mole of gas in the container)
Molecules make perfectly ______________ with the walls of the container and with each other.
elastic collisions
Other forces including ______________ are negligible.
gravity and attractions repesented by the Van der Waals constant (we need this for the assumption of identical values of a property in all directions, aka isotropy)
We can assume atoms have no ________________ energy except for transaltional energy
rotational or vibrational
Calculate translational energy.
KE= 1/2 mv^2 + 1/2 IW^2
A metal hoop of 3.0 kg and a radius of 0.80 m rolls down a hill.If the hoop has a translational velocity of 5.0 m/s at the bottom of the hill, calculate the total kinetic energy of the hoop.
m = 3.0 kg
v = 5.0 m/s
r = 0.80 m
__________________
I = mv^2
I = (3.0)(0.80)²
I = 1.92 kgm^2
____________________
W = v/r
W = (5.0)/(0.80) = 6.25 rad/s
_________________
KE = 1/2 mv^2 + 1/2 IW^2
KE = 1/2 (3.0)(5.0)² + 1/2 (1.92)(6.25)²
KE= 37.5 J + 37.5 J
KE = 75.0 J
The total kinetic energy of the hoop is 75.0 J.
What is Newtons 3rd law? Give an example of how it relates to Kinetic energy.
For every action (force) in nature there is an equal and opposite reaction.
Collision of a gas molecule with the walls of a container, exerts a force on the wall.
