# Shared Flashcard Set

## Details

Physics
Chapters 6 and 7--dimensional motion and gravitation
31
Physics
11/15/2012

Term
 What is a projectile?
Definition
 anything that's tossed, thrown, or dropped in a gravitational field
Term
 Which velocity stays constant during the flight of a projectile?
Definition
 x component
Term
 What is the only equation you use with the horizontal motion of a projectile?
Definition
 Vx=x/t
Term
 What velocity component in affected by the acceleration of gravity?
Definition
 y component
Term
 What equations do you use with the veritcal component?
Definition
 Y=Vyi(t)-1/2gt^2
Term
 What is the first thing you do in solving a horizontally shot projectile?
Definition
 find time
Term
 If a projectile is short horizontally from a height of 7 m with a horizontal speed of 20 m/s how far away will it land?
Definition
Term
 IF an object is thrown horizontally and another object is dropped at the same time, which object will hit first?
Definition
 they will hit at the same time
Term
 What are the steps in solving projectiles shot at general launch angles?
Definition
 Find the x and y components
Term
 What are the chracteristics of the flight of a projectile shot over a level surface?
Definition
 tiem up=time down; x is constant
Term
 At what angle will a projectile have the longest range?
Definition
 45 degrees
Term
 What is uniform circular motion? Is an object in uniform circular motion accelerating?
Definition
 when an object is moving in a circular path at a constant speed; yes it is accelerating because it is changing direction
Term
 What forces cuases an object to follow a circular path? What is the equation?
Definition
 centripetal force; Fc=mv^2/r
Term
 What is the source of the centripetal force?
Definition
 any of the common forces (gravity, friction, tension, normal)
Term
 What is the equation to find minimul velocity for an object to complete a vertical circle?
Definition
 Vmin=square root of (rg)
Term
 Who were tycho brahe and johannes kepler?
Definition
 Tycho was a dane who had an observatory who kept accurate records of the movement of the planets. Kepler knew Tycho had the data, went to work for Brahe and stole the data and created the 3 laws of planetary motion
Term
 What is the universal law of gravitation?
Definition
 the force of gravity is directly proportional to the products of the masses and inversely proportional to the distance squared
Term
 What are the three laws of planetary motion?
Definition
 1. all planets about the sun in ellipses2.a planet sweeps out equal areas at equal time (palnets speed up as they approach the sun)3. law of periods--the ratio of the period squared to the radius cubed is a constant
Term
 What is an inverse square law?
Definition
 double the distnace, the inverse square is 1/4
Term
 Who determined the universal gravitation constant?
Definition
 Henry Kavendish
Term
 What is a gravitational field?
Definition
Term
 What is an astronomical unit?
Definition
 distnace from earth to sun
Term
 What is perturbation?
Definition
 a deviation from a normal orbit
Term
 What planets were discvoered because of perturbation?
Definition
 Neptune, Pluto
Term
 What is a force field?
Definition
 an area around an object in which a force can be felt
Term
 HOw does the gravitational field change as you go beneath the surface of the earth?
Definition
 it decreases
Term
 What the value of the gravitational field at the center of the earth?
Definition
 zero
Term
 Any force can be centripetal if it _____.
Definition
 makes something go in a circle
Term
 What are the two components of velocity?
Definition
 gravity and horizontal velocity
Term
 What are three characteristics of the horizontal component of velocity?
Definition
 it is constant, not accelerated, not influenced by gravity
Term
 What are two chracteristics of the vertical component of velocity?
Definition
 it undergoes accelerated motion and it is accelerated by gravity
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