Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

Normal Size Small Size show me how

Normal Size Small Size show me how

# Dynamics chapter 1

### Notes, Test, Homework

Question | Answer |
---|---|

Order of Magnitude Reasoning | quick approx answer to a problem. |

Scale analysis | how big are the terms in an equation? want to throw out the unimportant terms -estimating typical order of magnitude of terms in governing equations |

Newtons 2nd Law | F=Ma can use because earth's atmosphere has mass |

contiuum mechanics | object is a tiny infintesimal chunk of fluid(liquid or gas) or an elastic solid -dynamics os branch of this |

What 2 forces act on blobs of air? | body forces and surface forces |

body force | force on an object is proportinal to mass of object. Force due to action at a distance ex: gravity |

surface force | forces on an object is porportional to surface area of object. force due to contact of object with surroundings. force exerted on surface of fluid element by outside fluid ex: pressure force, friction |

Pressure Gradient Force | considering the net pressure forece acting on a blob of air force is proportional to gradient of p -acts in opposite direction of grad p |

Gravitational Force | applies to 2 forces w mass M and m. |

Viscous force | Friction force -force due to molecular friction |

inertial reference frames | non accelerating frames -stationary or moves at constant velocity F=Ma is with real forces(only true for intertial reference frames) |

non-inertial reference frame | speeds up or rotates -it accelerates -we use this one because fixed point on earth(earth rotates) |

F=ma can be modified to use for non-inertial frame. Introduce what 2 apparent forces? | apparent force=due to acceleration of the reference frame -centrifugal and Coriolis force |

geopotential? | work pum required to lift a mass from earth's surface to a height z |

latitude | rotation east and west for spherical coords |

meridian | rotation north and south for spherical coords |

Exact way, almost exact way, quick-n-dirty way are used to find what? | distances due to coriolis force. hockey puck |

if atmosphere is at rest then... | coriolis force=0 friction=0 acceleration=0 p isnt a function of x or y so have hydrostatic equation |

density is bigger for ___ air | colder |

relation between definite integral and average | average=have a dependent variable, independent variable and interval of independent variable. |

independent variable | time or space |

dependent variable | temp, pressure, u or v |

hypsometric equation | transform hydrostatic equation to treat z as dependent variable and p as independent variable |

thickness is proportional to ___ in a layer | temperature |

when to use isobaric coords? | when hydrostatic approx is available -uses pressure as the vertical coord(not z) |

lagrangian | describe how quantities change with time for an air parcel following the motion |

dependent variables of lagrangian | x(t), y(t), z(t) |

independent variables of lagrangian | t |

Eularian | describe how quantities change with time at a fixed point in space(not following blob) |

independent variables of eularian | x(t), y(t), z(t), t |

degrees into radians | multiply degree by 2 pi/360 |

typical radius for low pressure system | 1000 km |

typical radius for a tornado | 100 m |

typical horizontal length of tornado | 100m-1000m |

typical horizontal length of cumulonimbus | 1 km-10 km |

typical horizontal length of fronts (width) | 10 km-100 km |

typical horizontal length of H or L pressure systems | 1000 km |

starting point for dynamics is ___. translate this law into different equations to understand/predict air morion(weather) | newtons 2nd law |

F=ma means | sum of forces acting on object=mass of object+acceleration of object |

a=? | Dv/Dt v= velocity |

V=? | Dr/Dt r=position vector |

pgf equation? | F/m=-1/row(grad p) |

magnitude of grad p is big when | there is close packing of isobars |

newtons law of gravitation? | Fg=(-GMm/r^2)(r vector/r) Fg= gravitational force on m due to M |

r vector | directed distance between 2 masses, points from big mass M to little mass m |

rvector/r | r hat (is of unit length) |

Fg is ___ proportional to the square of the distance between 2 masses | inversely |

G | universal gravitational constant 6.67*10^/-11 Nm^2/Kg^2 |

g* | Fg/m gravitational force per unit mass |

a | 6370 km |

in troposphere, z<__km so r=Z+_=_ | 15, a,z |

mass of earth | M=4/3(pi)(a^3)(density of earth) |

N | kg*m/s^2 |

density of earth | 5520 kg/m^3 |

no-slip condition | molecular friction causes fluid to stick to solid objects/boundaries |

steady state condition | d( )/dt=0 stops changing in time |

sheearing stress | proportional to vertical derivative of x-comp velocity |

newtons 3rd law | fluid below box above it exerts equal and opposite force on bottom face |

real forces | gravitational, pgf, viscous force |

earth rotates with angular velocity __ | omega |

if rotating, observers in that reference frame are ___ to be subject to a ___ force | perceived, centrifugal |

gravity force pum | gravitational force pum + centrifugal force pum |

centrifugal force= | m*omega^2*R(vector) |

u absolute= | omega*R |

magnitude of omega= | 7.27*10^-5 1/s |

coriolis force= | m(-2omegaxu) |

components of coriolis force | Fx=m(2omegavsin(latitude)-2omegawcos(latitude)) Fy=m(-2omegausin(latitude)) Fz=m(2omegaucos(latitude)) |

if puck stays on flat ice | z(t)=constant so w(t)=0 |

horizontal equations of motion(with w=0) | du/dt=2omegavsin(latitude) dv/dt=-2omegausin(latitude) |

f | 2omegasin(latitude) |

hydrostatic equation is an ___ equation for ___ atmosphere | exact, resting |

hydrostatic is a good approx for real moving atmosphere except when | vertical accelerations are large (supercell, tornado) |

integrating hydrostatic shows | at any point in the resting atmosphere, pressure=weight(per unit area) of all air above it |

p(H) | (e^-1)Po |

___ on constant z-surface carry same info as height contours on ____ | isobars, isobaric surface |

local derivative of T used for | eularian |

geosynchronous orbit | hover over the same location on earth -angular velocity of object and eaerth are the same |

absolute | as observed in an inertial reference frame |

Created by:
leebee05