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Astronomy Chapter 4
Astronomy
| Question | Answer |
|---|---|
| speed | how far an object will travel in a certain amount of time |
| velocity | how far and in what direction an object will travel |
| acceleration | change in velocity |
| acceleration of gravity | acceleration of a falling object in m per sec |
| momentum | product of mass times velocity |
| force | change applied to an object's momentum |
| net force | overall force acting on an object |
| angular momentum | circular momentum |
| torque | twisting force that can change an objects angular momentum |
| mass | amount of matter |
| weight | force that a scale measures |
| free-fall | falling without resistance |
| weightlessness | in a state of free-fall |
| Newton's First Law | An object moves at constant velocity if there is no net force acting upon it |
| Newton's Second Law | Force = mass x acceleration (F=ma) |
| Newton's Third Law | For any action, there is an equal and opposite reaction |
| conservation of momentum | total momentum of interacting objects cannot change |
| conservation of angular momentum | as long as there is no external torque, the total angular momentum of interacting objects cannot change |
| conservation of energy | energy cannot appear out of nowhere or disappear into nothing |
| kinetic energy | energy of motion |
| radiative energy | energy carried by light |
| potential energy | stored energy |
| thermal energy | collective kinetic energy moving within a substance |
| temperature | measures average kinetic energy of particles |
| gravitational potential energy | how much mass an object has and how far it can fall |
| mass-energy | energy contained in mass itself (E=mc^2) |
| law of gravitation | Fg = GM1M2/d^2 |
| bound orbit | ellipse |
| unbound orbits | ellipse, parabola, hyperbola |
| gravitational encounter | when two objects pass close enough to exchange orbital energy |
| escape velocity | amount of energy needed by an object to clear a gravitational field of orbit |
| tidal force | difference in gravitational forces that causes two tidal bulges |
| tidal friction | tidal forces stretching the earth |
| synchronous rotation | moon always shows the same face to Earth because of tidal friction |