Details Title: ASTRONOMY CHAPTER 5 Description: From book and outline paper Total Flash Cards: 46 Created: 03/05/2009 15:54:40		New Users: To study from this flashcard set, or to create your own your own study flash cards, REGISTER HERE. Existing Users: CLICK HERE. Additional Astronomy Flashcards
Cards in this set: Term What is the modern term for the steady increase in the velocity of a falling body by 9.8m/s? Definition Acceleration of gravity Term Galileo discovered that acceleration of a falling object doesn't depend on what? Definition weight Term What is Newton's first law of motion? Definition A body continues at rest in uniform motion in a straight line unless acted upon by some force Term what is Newton's second law of motion? Definition The acceleration of a body is inversely proportional to mass, directly proportional to force, and in same direction as the force Term What is Newton's third law of motion? Definition To every action, there is an equal and opposite reaction Term What is momentum? Definition the tendancy of a moving body to keep moving; rate of motion Term And object's momentum is equal to velocity times what? Definition mass Term AN EXAMPLE OF MOMENTUM IS... Definition to toss a paper clip, it has low velocity and little momentum. A speeding bullet has high velocity and high momentum. Term Momentum depends on velocity and what? Definition mass Term What is velocity? Definition a directed speed Term What is acceleration? Definition change in velocity Term What does the equivalence principle state? Definition says that there is no observation you can make inside a closed spaceship to distinguish uniform acceleration and gravitation Term What do physcists refer to gravity as? Definition curvature Term What is the difference between Natural Motion and violent motion? Definition Natural Motion: a displaced object returns to it's natural place and motion Violent Motion: a motion sustained by force Term What the steady rate for acceleration of gravity? Definition 9.8m/s^2 (32m/s^2) Term Galileo stated the Law of Inertia, which is what? Definition in the absence of friction, a moving body on a horizontal plane will continue moving forever Term What was Newton's first law of gravity based on? Definition Galileo's law of Inertia Term What is mass? Definition amount of matter in a body Term what is the difference between a hypothesis and theory? Definition hypothesis: a single statement subject to testing theory: an elaborate system of rules and principles that have been tested and applied Term What is a natural law? Definition A theory that has been so thoroughly tested that scientists have great confidence in it Term Newton discovered that the curved path of the moon meant what? What did it require? Definition It meant that it was being accelerated away from a single-path line and it required the prescense of force-gravity Term What was Newton able to demonstrate about the force of gravity? Definition the force of gravity between two objects is proportional to the product of their masses and obeys the inverse square law Term what is the inverse square law? Definition the force of gravity is inversely proportional to the square of the the distance between the two objects Term what term do scientists use to describe how gravity can act at a distance? Definition Field Term How does gravity explain orbital motion? Definition Objects around earth are falling (being accelerated) toward Earth's center through gravity, and therefore, orbit the earth instead of follow a straight line Term If there is no friction, what would happen? Definition the object will fall around it's orbit forever Term If an object is in a closed orbit, what kind of path is it following? Definition elliptical path Term To follow a circular orbit, an object must orbit with what? Definition circular velocity Term what is the term for orbits that never return to their starting points? Definition open orbits Term Two objects in orbit around each other actually orbit around what? Definition their common center of mass Term What do Newton's laws explain? Definition Kepler's three laws of planetary motion Term the planets move faster when closer to the sun and slower when farther away for what reason? Definition they conserve angular momentum Term what is the difference between energy, kinetic energy, and potential energy? Definition energy: ability to produce a change Kinetic Energy: an objects energy of motion Potential Energy: the energy an object has because of its position in a gravitational field Term what is the unit of energy? Definition Joule Term What causes tides? Definition caused by differences in the force of gravity acting on different parts of a body Term how does the moon's gravity affect tides? Definition moon's gravity pulls more strongly on the near side of Earth than on the center of Earth. Term what are spring tides? Definition tides produced by the moon combined with tides produced from the sun at New and Full Moons. Term What are Neap Tides? Definition when the sun and moon work against each other to produce less extreme tides at quarter moons Term How did Einstein describe motion and gravity? Definition his special theory of relativity and general theory of relativity Term What does special relativity say? Definition says that uniform motion is relative (observers cant detect their uniform motion through space except by outside objects). This is known as the first known postulate Term what is the second postulate (after special relativity)? Definition the speed of light is constant Term in special relativity, what two things are related? Definition mass and energy Term what is the general theory of relativity? Definition says a gravitational field is a curvature of space-time caused by presence of a mass. Term if u drop a feather and a steel hammer on the moon, they should hit at the same moment. Why doesnt this happen on Earth? Definition air resistance slows down objects Term What is the differnce between mass and weight? Definition mass is matter in an object weight is the force of gravity Term an object when in an elliptical orbit, when farthest from earth, has a higher or lower velocity? Definition lower. (its velocity is higher when its closer)