Module 3 Flashcards
How is energy transferred?
From regions of high temperature to regions of low temperature.
Thermal equilibrium
When two objects are in contact with each other and are the same temperature, there is no net transfer of energy between them.
Celsius to kelvin?
Add 273K
What is the celcuis scale based on?
Freezing and boiling point of water
What are the problems with the celcuis scale?
The boiling and freezing point changes according to pressure
What is the arrangement of solids?
Particles vibrate in a fixed position
If temperature increases the amplitude of vibration increases.
Spacing between atoms are very small
What is the arrangements of liquids?
The particles can flow past each other. They vibrate but not in a fixed position.
What is the arrangement of gases?
Particles are far apart. They don’t exert forces on each other expect during collisions. Particle move in random morion
How can brownian motion be demonstrated?
Using smoke cells or pollen grains in a liquid.
Observation seen in brownian motion?
The smoke particles move in random motion. The air particles cannnot be seen
What are the conclusions from brownian motion?
The smoke particles are colliding with the air particles, which must also be moving in random motion. The air particles must be smaller then the smoke cells.
Internal energy
The sum of the randomly distributed kinetic energy and potential energy of all particles of a substance
When a substance is changing state, what energy increases?
KE is constant. PE is increasing by breaking the bonds.
Temperature is constant.
Specific heat capacity
The energy to raise the temperature of 1 kg of a substance by 1 K
What is specific latent heat?
The energy per kg required to change its state without changing its temperature.
Specific latent of fusion
The energy per kg required to melt a substance at a constant temperature
Specific heat of vaporisation
The energy per kg required to vaporise a substance at a constant temperature
Heat
Type of energy (J)
Temperature
Measure of hotness of an object (K)
.
.
B
D
What is the molar mass?
Tells us how much the mass of one mole of a substance weighs.
Eg. Water = 18g/mole
How do you find the number of atoms or molecules?
Moles X avogadro
Why do we use root mean squared speed?
Many different particles have different speeds. So you can find the average velocity using this.
Assumptions:
R-Random motion. large number of particles have rapid,random motion
A- Attraction. Negligible forces of attraction between particles except during collisions.
V-Volume. Individual particles occupy negligible volume compared to the volume of gas.
E-Elastic collisions.
D-Duration of collisions. Time spent in collisions is negligible compared to time spent between collisions.
What are the forces of ideal gases?
Zero forces except during collisions.
The potential energy is assumed to be 0.
PV=nRT
n= number of moles
R= gas law constant
PV=NKT
N= number of particles
K= Boltzmann constant
PV=NKT
N= number of particles
K= Boltzmann constant
Boyle’s law
Temperature is constant for fixed amount of gas.
PV= constant
P= constant/V
Pressure is inversely proportional to volume.
Charles’ law
Volume = constant n= constant
PV=nRT
P=nR/V X T
P= constant X T
Pressure is directly proportional to temperature
What is the centripetal force?
Net constant force which causes an object to move in a circular path
What is the direction of centripetal force?
It is always directed towards the centre of the circle
Which direction is the centripetal force compared to velocity
Perpendicular to the velocity of the object.
How can you have acceleration at constant speed?
Velocity is a vector quantity and the magnitude remains the same but the direction changes. The centripetal acceleration causes the change in direction.
Why does the speed of an object in circular motion not change?
The net force is directed perpendicular to the direction of motion( the velocity: this means that there is no work done by the force and hence no change in speed.
For an object to be moving in circular motion what is required?
The force is constantly acting 90 to the objects velocity (towards the centre of the circle).
A object travelling in a loop what is the force at the bottom?
The centripetal force at the bottom has to provide for the weight too.
S= centripetal force + weight
An object travelling in a loop what is the force at the bottom?
The weight is acting downwards so-
S= centripetal force - weight
Angular frequency
The rate of change of angular displacement.
What are the two characteristics of simple harmonic motion?
The acceleration is proportional to the displacement.
The acceleration is always directed towards the equilibrium position.
A against X grapgh
Straight line through the origin.
Gradient negative
A proportional to X
At t=0 the oscillator is at the amplitude what is the equation?
X= Acos(wT)
At t=0 the oscillator is at the equilibrium what is the equation?
X= Asin(wt)
What are the effects of damping?
Amplitude decreases.
The time period remains the same so the frequency remains the same.
In SHM the time period is independent of what
Of the amplitude
In SHM the time period is independent of what?
Amplitude 2
Free oscillator
The system is disturbed once and then oscillates with no external forces.
Forced oscillation
A driving force is applied during the oscillations
A free oscillator will be moving at?
Natural frequency
What is the natural frequency?
The frequency at which an object will oscillate after an initial disturbance.
If the driving force matches the natural frequency what occurs?
Resonance occurs and the amplitude increases.
During damping what happens to the graph?
Amplitude decreases and the peak occurs at a lower frequency
What are the conditions required for SHM?
Acceleration (force) acts in the opposite direction to the displacement.
Acceleration is proportional to displacement.
What is resonance the opposite of?
Damping
What are gravitation fields caused by?
An object having mass
The more the field lines..
The stronger the gravitational field
Close to the surface of earth what is assumed about the gravitational field strength?
The field strength is uniform
What is the speed of an object when it is closer to the sun compared to when its further away?
It speeds up closer to the sun as it experience more of a gravitational force.
What is speed of an object closer to the sun compared to one further away from the sun?
The speed is faster closer to the sun as it experience more of a gravitational force
Geostationary satellites
Have an orbital period of 24 hours about the equator.
The remain fixed to the sky to an observer on Earth.
What does the area under a force against distance represent?
The work done
define angular velocity
the rate of change of angle.
Where does a centripetal force act upon?
it is always perpendicular to the velocity of an object. This means this force has no component in the direction of motion therefore no work is done on the object. This means that the speed is constant.
What is the relationship between the angular velocity and the linear velocity?
for objects with the same angular velocity, the linear velocity at any point is directly proportional to the the radius of that object.
How do you find mass from molar mass?
Mass = molar mass/avogadros constant
Why is solid water less dense then liquid water?
As the molecules are held slightly further apart than in their random arrangement so ice is less dense
How do atoms or mole cause pressure?
The milcules are always kiving and exert a force on the walls and
At absolute zero what is the pressure of the gases?
The pressure must be zero as the particles aren’t moving and the potential energy is at a minimum.
How do temperature and internal energy correlate?
Ideal gas: particle don’t have electrostatic forces except during collisions. So there is no electrical potential energy so all the internal energy is in the form of kinetic energy.
Why does the centripetal force not affect the direction of motion?
It is always perpendicular to the velocity of the object so it does no work on the object
For objects with the same angular velocity what is the linear velocity equal to?
Linear velocity is directly proportional to the radius.
