Physics

Question 1

SI units

Answer 1

• meter
• kilogram
• second
• newton (force) = kg*m/s²
• joule (work/energy) = kg*m²/s²
• watt (power) = kg*m²/s³

Question 2

Newtons First and Second Law

Third Law

Answer 2

First: F_net = ma = 0

Second: F_net = ma

Third: To every action there is alwats an opposed but equal reaction

Question 3

Conservative and Nonconservative forces

Answer 3

Conservative: gravity, electrostatic

Nonconservative: friction, air resistance

• dissipate mechanical energy as thermal or chemical

Work done by nonconservative forces equals the change in mechanical energy (PE and KE)

Question 4

P-V graph

Answer 4

• gas expansion and compression
• x axis: volume
• y axis: pressure
• area under the curve is the work done by the gas
• W = P(Vf - Vi)

Question 5

Simple machines

Answer 5

inclined plane

wedge

wheel and axle

lever

pulley

screw

Question 6

Thermal Vocab

Answer 6

• temperature - proportional to kinetic energy of particles
• heat - transfer of thermal energy from hotter to colder object
  
  • thermal equilibrium - no heat transfer

Question 7

Third Law of Thermodynamics

Answer 7

• entropy of a perfect crystal is zero at absolute zero

Question 8

Type of System

Answer 8

• Isolated - cannot exchange energy or matter with surroundings
• closed system - capable of exchanging energy but not matter
• open system - can exchange matter and energy

Question 9

State vs process function

Answer 9

process function - describe path to get from one state to another

• work and heat

state function - function of current equilibrium state

• independent of path taken
• pressure ,density, temperature, colume, enthalpy, G, S

Question 10

First Law of Thermodynamics

Answer 10

• change in total internal energy is equal to the amount of energy transferred in the form of heat minus the work transferred
• Change in U = Q - W

Question 11

Second Law of Thermodynamics

Answer 11

• objects in thermal contact will exchange heat energy until at thermal equilibrium
• 1 kcal = heat required to raise 1 kg of water 1 degree

Question 12

Heat transfer types

Answer 12

• Conduction - direct transfer of energy from molecule to molecule thorugh molecular collisions
  
  • required physical contact
• convection - transfer of heat by physical motion of a fluid over a material
  
  • only liquids and gases
• Radiation - transfer of energy by electromagnetic waves
  
  • sun, radiation oven

Question 13

Specific heat

Answer 13

• amount of energy required to raise one gram of the substance by one degree
• water: 1 cal/(g*k)

Question 14

Phase Changes

Answer 14

• solid to liquid: melting, fusion
• liquid to solid: freezing, solidification
• liquid to gas: boiling, evaporation, vaporization
• gas to liquid: condensation
• solid to gas: sublimation
• gas to solid: deposition

Question 15

Thermodynamics with constant variables

Answer 15

• isothermal Q = W
• adiabatic (Q = 0) deltaU = -W
• Isobaric: constant pressure
• Isochoric: constant volume
  
  • W = 0 and deltaU = Q

Question 16

Entropy

Answer 16

• measure of spontaneous dispersal of energy at a given temperature

Question 17

Specific gravity

Answer 17

• density of object compared to water
• used to determine if object sinks or floats
• density of object divided by 1 g/cm³
  
  • 1 g/cm³ is the density of water

Question 18

Absolute pressure

Answer 18

• aka hydrostatic pressure
• addition of atmospheric pressure and pressure from fluid

Question 19

Gauge Pressure

Answer 19

• difference between absolute pressure inside the tire and atmospheric pressure outside the tire
• = P - P_atm

Question 20

Pascals Principle

Answer 20

• incompressible fluid, change in pressure will be applied to all of the fluid and to the walls of the container
  
  • ex. squeezing a closed bottle until cap bursts off and liquid squirts out
• hydraulic system
  
  • apply force over small area and displace a volume of fluid
  • same volume of fluid displaced on other hydraulic surface to lift the object

Question 21

Buoyancy

Answer 21

• compare density of object to density of fluid
• percent submerged is equal to the specific gravity of the object compared to the fluid

Question 22

cohesion and adhesion

Answer 22

• cohesion : attactive force between like molecules
• adhesion : attractive force between different molecules

Question 23

Fluid dynamics

Answer 23

• viscosity - resistance of fluid to flow
  
  • increase viscosity, increases viscous drag
• inviscid - no viscosity
• laminar flow - smooth and orderly, as layers that are parallel
  
  • Poiseuille’s law - rate of flow in tube
    
    • radius is exponential to the 4th power
    • length is in denominator
• Turbulent flow - forms eddies (swirls of fluid)
  
  • can be caused by unobstructed fluid at critical speed
• streamlines: visual representation of flow in a tube

Question 24

Bernoulli’s Equation

Answer 24

• shows principles of conservation in regards to fluid pressures
• includes
  
  • absolute pressure
  • dynamic pressure - associated with movement of fluid
  • gravitational pressure
• when velosity increases, absolute pressure decreases
• Venturi flow meter - used to show that absolute pressure decreases as velosity increases due to tube narrowing
  
  • venturi effect - height of fluid in venturi tube decreases