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gravitational force between two objects
Gm1m2/r^2
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what keeps an object in its circular pathway?
centripetal force
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work done by nonconservative force
=change in Energy (change in potential energy plus change in kinetic energy)
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when can we say work is done in a system?
when volume of the system is changed due to an applied pressure.
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work
- Fdcos (theta)
- area under PV graph
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when a gas expands is work positive or neg?
work is positive (work was done by the gas)
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isochoric
same as isovolumetric
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power
- work done per unit time
- watt
- J/s
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work energy theorem
work done is equal to change in KE
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first law of thermodynamics
change in internal energy = heat transferred into the system - work done by the system
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mechanical advantage
ratio of magnitudes of force exerted on an object by a simple machine to the force actually applied on the simple machine
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efficiency
- work output/ work input
- work input is the product of (effort)(effort distance)
- output (load x load distance)
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kelvin to celsius
K=C+273
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Fahrenheit to Celsius
F=(9/5)C+32
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thermal expansion
change in length= (coefficient of linear expansion) (original length) (change in temp)
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isolated system
- not capable of exchanging energy or matter
- total change in internal energy is zero
- insulator (calorimeter)
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closed system
- capable of transferring energy
- movable pistons and gases are examples
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state function
- independent of path taken to reach a particular equilibrium state
- function of only the current equilibrium state of a system
- Pressure, density, temp, volume, enthalpy, internal energy, Gibbs free energy, and entropy.
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how does one change the internal energy?
- increasing the temperature in the system
- (increase-pos, decrease-neg)
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when is work positive for a system?
- work is positive when system expands
- work is neg when system compresses
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1 cal is how many joules
4.184
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convection
- transfer of heat by physical motion of fluid over material.
- only liquids and gases
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radiation
transfer of energy by electromagnetic waves, can transfer energy through vaccum
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specific heat
- amount of heat required to raise 1 g of substance by one degree Celsius or kelvin
- for liquid that is 1cal/(g K) or 4.184J/(g.K)
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heat equation
- q=mc (change in temp)
- c=specific heat)
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which has greater kinetic energy at the same temp: liquid or solid
even though liquid water has greater number of microstates (increase freedom of movment), KE is the same as solid water at same temp.
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equation for heat during phase change
- q=mL
- (m is the mass of substance)
- L=constant
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units for entropy
- J/ (mol.K)
- entropy of the universe is always increasing
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fluid characteristics
ability to flow and conform to shape of the container
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specific gravity
when density of fluid is compared to that of pure water 1g/cm^3
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what is pressure in terms of force and area?
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what is the pressure of air?
1.013 x 10^5 Pa=760 mmHg=760 torr=1atm
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hydrostatic pressure
p0+pgz
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force of buoyancy
density of fluid (V fluid displace) (g)
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cohesion vs. adhesion
- cohesion, attractive force that molecule of liquid feels toward other molecules of same liquid
- adhesion: attraction between water and another substance, backwards meniscus
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flow rate and radius and pressure gradient
- poiseuille's law
- flow rate is proportional to 4th power of radius, inversely proportional to pressure gradient
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continuity equation
vA=vA
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bernoulli's equation
P+1/2pv^2+pgh=P+1/2pv^2+pgh
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