What do we mean by acceleration? What is the acceleration of gravity?
Acceleration is when the velocity is changing speed or direction. No matter direction. So acceleration can be negative. Acceleration of gravity is the acceleration of a falling object. The # is 9.8 m/s with each second.
What is momentum? How can momentum be affected by a force? What do we mean when we say that momentum will be changed only by a net force?
Momentum is the product of its mass and velocity (momentum= m X v) Momentum can only be affected by a force applied to it- not only any force, but a net force or overall force. Therefore, a change in momentum occurs only when there is a net force that is
What is free-fall, and why does it make you weightless?
Free-fall means falling without resistance slowing you down.. Caused when the floor drops out from below you at the same rate that you fall allowing you to "float" above it. Imagine that floor was a scale and it would read zero.. therefore you'd be "weigh
The densities of Jupiter (1.33) the Sun (1.41) and Saturn's moons Dione (1.44) and Rhea (1.33) are all about the same in spite of having HUGE differences in gravity holding them together. Numerically how can this be? What is the underlying physical cause
Density is not determined by mass, but by how many molecules are in a certain amount of space. Therefore, the change in size between Jupiter, the Sun, and Saturn's moons would have no effect on their densities.
Ex. Hot oven versus boiling water.
** Becaus
State each of Newton's three laws of motion. For each law, give an example of its application.
1st law: An object in motion stays in motion. Technical terms, an object moves at constant velocity unless a net force acts to change its speed or direction
Ex. A spaceship needs no fuel to keep moving in space
2nd law: (Force= mass X acceleration) and al
What are the laws of conservation of momentum, conservation of angular momentum, and conservation of energy? For each, give an example of how it is important in astronomy.
Law of conservation of...
Momentum= the total momentum of interacting objects cannot change as long as no external force is acting on them.. aka. Total momentum is conserved.
Ex. Reps Newton's 1st law of constant motion b/c there's no net forces in space
Imagine you are out in space and push away from you an object having a mass identical to your own. What happens? Explain.
You would push whatever you jumped from in the opposite direction. Unlike Earth, you would continue one direction while the object would also continue the opposite direction. (As long as that object has no gravity pulling you back towards it.) b/c of cons
Define kinetic energy, radiative energy, and potential energy, for each type of energy, give at least two examples of objects that either have it or use it.
Kinetic Energy= energy of motion
Ex. Falling rocks
Ex. Orbiting planets
Radiative Energy= Energy carried by light
Ex. Lightbulb
Ex. The Sun and stars
Potential Energy= Stored energy
Ex. Rock perched on a ledge has gravitational PE
Ex. Gasoline contains ch
Define temperature and thermal energy. How are they related? How are they different?
Related b/c they're both measuring KE of particles. Different b/c thermal energy measures total KE of all randomly moving particles within something while temperature= measures average KE of the particles.
Ex. Hot oven versus boiling water. b/c of heat an
What do we mean by mass-energy? Is it a form of kinetic, radiative, or potential energy?
Mass-energy= A form of potential energy.. is the energy contained in mass itself. Basically Einstein said, mass is a form of potential energy and that it can be converted into other forms of energy.. E= mc^2... E=PE, m=mass, and c=speed of light
Summarize the universal law of gravitation in words.
Universal Law of Gravitation:
1. Every mass attracts every other mass through force called gravity.
2. Strength of gravitational force is directly proportional to product of their masses. (Doubling mass of one object doubles fore of gravity b/t the two.)
Consider an object shot upward from the earth with less than escape velocity. Describe its motion.
Escape velocity is 40,000 km/hr or 11 km/s. An object shot upward with less than that would orbit Earth at a lower height and in a more circular orbit. More orbital energy means a higher and more elliptical orbit.
Why do objects fall at the same rate?
Objects fall at the same rate b/c (d= REarth)... When you replace the bottom of the Fg equation... it ends up cancelling out mass. Therefore, mass does not affect the rate at which objects fall. Only acceleration of the object is left.
How could I double the Earth's escape velocity? [more than one way, but the universal gravitational constant remains the same.]
If you did the mass 4x its original. Or make the object's size 4x (?) smaller
What is the difference between a bound and an unbound orbit? What orbital shapes are possible?
Bound orbit= an object goes around another object over and over again (gravity creates a bond holding them together)
Unbound orbit= paths that bring an object close to another object just once (ex. Comets. Come in once to inner sol sys, loop Sun, and neve
State, then explain, Kepler's three laws?
Kepler's 3 laws of planetary motion:
1. The orbit of each planet around the Sun is an ellipse with the Sun at one focus (aka a planet's distance from the Sun varies during its orbit). Includes a perihelion and an aphelion (closest and furthest away points
How did Newton's understanding of gravity extend Kepler's Laws?
Newton's law of universal gravitation, which is an extension of Kepler's Laws, explains stable orbits (like the orbit of a satellite around Earth or of a moon around a planet). Newton just expanded upon Kepler's description of orbital things by proving to
What quantities do we need to know if we want to measure an object's mass with Newton's version of Kepler's third law? Explain.
You need to know the orbital period of the two objects (p), the mass of one of the objects (M1), the distance between their centers (a), and the gravitational constant. HOWEVER what we learned is that if one object is massive (like the Sun,) then we don't
Explain why orbits cannot change spontaneously. How can a gravitational encounter cause an orbit to change? How can an object achieve escape velocity?
Orbits cant change spontaneously because as long as no other object causes the planet to gain or lose energy, its orbit must remain constant. However, they do sometimes change because of gravitational encounters- when two objects get close enough that the
Explain how the Moon creates tides on Earth. Why do we have two high and low tides each day?
Basically, the strength of gravity between the Earth and the Moon declines with distance so as we switch b/t the sides of the Earth that face the Moon, the gravitational attraction of each part of Earth closest to the Moon becomes weaker. This difference
How do the tides vary with the phase of the Moon? Why?
There are two types of tides including Spring and Neap tides. When the Sun and Moon work together (both horizontally), you get Spring tides, which occur at new and full Moons. When the Sun and the Moon work against each other (one horizontal and one verti
How would you make ocean tides stronger or weaker? More or less frequent? [Be careful to state what you would change and what effect it would have on the frequency of tides.]
If the Earth had synchronous rotation and was closer to the Moon, then we would see stronger ocean tides, but they would occur less frequently. The synchronous rotation would cause the frequency to be less often because the Earth's rotation through the bu
Describe the tides (if any) if we had no moon.
If we had no moon, the tides would still exist, but be a little less than half the change each day. These tides would be caused by the Sun. They would occur every 12 hours.
What is tidal friction? What effects does it have on Earth? How does it explain the Moon's synchronous rotation?
Tidal forces stretch the actual Earth, which creates tidal friction. Basically, the Moon's gravity tries to keep the tidal bulges on the Earth-Moon line, but Earth's rotation tries to move the bulges around with it. This causes two things to happen to Ear
Would you fall at the same rate on the Moon as on Earth?
No, gravity is not the same on the Moon; therefore, your acceleration would be much different. (much slower fall back to Moon after you jumped) b/c although your distance is smaller (16 on the bottom) so is the size of the Moon. (80th x smaller)