The Universe in a Toy 1.Speed, velocity, acceleration 2.Acceleration due to gravity 3.Kinetic Energy 4.Thermal Energy 5.Gravitational potential energy 6.Electric potential energy 7.Momentum 8.Conservation of energy and momentum 9.Conservation of angular momentum 10.Inertia (Newton's First Law) 11.Newton's Second Law 12.Newton's Third Law, Part 1 13.Newton's Third Law, Part 2 porcelain enamel ceramics. References Ehrlich, Robert, "Why Toast Lands Jelly-Side Down," 1997 (Princeton University Press, Princeton) Ehrlich, Robert, "Turning the World Inside Out," 1990 (Princeton University Press, Princeton) Taylor, Beverley A.P., Poth, James, Portman, Dwight J., "Teaching Physics with Toys," 1995 (Learning Triangle Press, Middletown, OH) Bloomfield, Louis A., "How Things Work," 1997 (John Wiley & Sons, New York) 1. Speed, Velocity, Acceleration Speed: The change in distance over a given time interval, measured in km/sec, or m/sec (for example). Velocity: 1) The change in distance in a given direction over a corresponding change in time; 2) Speed with an attitude. Acceleration: A change in the magnitude or direction of the velocity. Materials Wind-up toy Ruler Stop watch Procedure Using the ruler and the stop watch, find the speed of the toy by calculating the distance (in millimeters) the wind-up toy moved over a given time interval. Demonstrate or explain "speed," hopefully keeping the wind-up toy going in a certain direction. Demonstrate or explain "acceleration." Use the equations: speed = [distance traveled] / [time it took] s = x/t Put in some figures and calculate the speed (average velocity). Questions How do you know something is moving? When you see a object moving backward or forward or sideways or up or down. What does it mean to say something is moving faster or slower than something else? Accelerating is moving faster and decelerating is moving slower. When something is moving faster at 55 mph or slower at 30 mph. How does velocity differ from speed? Velocity is a measure of a bodies speed and direction Velocity is galaxies moving farther away from each other is known as the red shift. As light from distant galaxies approach earth there is an increase of space between earth and the galaxy, which leads to wavelengths being stretched. The Hubble Law is a observed relationship between recession velocity determined from redshifts and distance determined independently using standard candles, etc. the object's recessional velocity. What is acceleration (deceleration)? Acceleration is speeding faster, and deceleration is slowing down. Acceleration is a change in a bodies speed or direction of motion When radar catches you going above the speed limit, are you getting a ticket for "speeding" or "velocitying"? Yes for speeding. 2. Acceleration Due to Gravity Materials Marbles of various sizes An extremely light ball of comparable size to one of the marbles Procedure Newton's law of universal gravitation is written as: Fg = G (M1M2)/D2 Explain each symbol and the whole equation. For an object on or near the surface of the Earth, D is approximately equal to the radius of the Earth. F is for force g is for gravity G gravity M is Mass 1 M is Mass 2 D Distance. Marbles small size can be tossed in the air faster. Explain the basics of the universal law of gravity: one explains then moon's orbit by reasoning from the motion of a falling apple by measuring how far it falls in one second. Newton's laws of motion and his law of universal gravitation provided a theoretical explanation for Kepler's empirical laws of planetary motion. Because the Sun and a planet feel equal and opposite gravitational forces by Newton's third law, the Sun must also move (by Newton's first law).

astro101a02.html Assignment 2 Review and Thought Questions From the text: pages 54-55: 4, 5, 9, 11, 12 (#21 is optional) Chapter 2 4. Explain how Kepler was able to find a relationship (his third law) between the periods and distances of the planets that did not depend on the masses of the planets or the Sun. Kepler's third law States that the square of a planet's orbital period is proportional to the cube of its average distance from the Sun (semimajor axis), which tells us that more distant planets move more slowly in their orbits. In its original form, written p2 = a3. See also Newton's version of Kepler's third law. 5. Write out Newton's three laws of motion in terms of what happens with the momentum of objects. Newton's first law of motion States that, in the absence of a net force, an object moves with constant velocity. Newton's second law of motion States how a net force affects an object's motion. Specifically: force = rate of change in momentum, or force = mass acceleration. Newton's third law of motion States that, for any force, there is always an equal and opposite reaction force. 9. What is the momentum of a body whose velocity is zero? How does Newton's first law of motion include the case of a body at rest? Newton's first law of motion States that, in the absence of a net force, an object moves with constant velocity. 11. A body moves in a perfectly circular path at constant speed. Are there forces acting in such a system? How do you know? You float while inside a space station. Your in a free falling weightless environment. Gravity is less inside a space station while gravity is strong on Earth. 12. As air friction causes a satellite to spiral inward closer to the Earth, its orbital speed increases. Why? Friction and Gravity may have a effect on the satellite by causing the satellite to fall into the earth faster.. 21, Newton showed that the periods and distances in Kepler's third law depend on the masses of the objects. What would be the period of revolution of the Earth (at 1 AU from the Sun) if the Sun had twice its present mass? Activity 1: "The Universe in a Toy" A Student Activity Using Toys to Demonstrate the Physics of the Universe Introduction Modern-day astronomy is the application of terrestrial physics to the rest of the Universe. The move from superstition and astrology to a mathematical view of our cosmos was secured by the extensive work of Sir Isaac Newton. The work of Newton and others to follow led to our understanding of the physical Universe. So fundamental are these concepts today and so pervasive in our everyday life, the physics can be demonstrated using toys! One of the top ten reasons to become a physicist: you get to play with toys (sometimes really big toys, like rockets, or for astronomers, huge telescopes). Each of the following topics leads to a demonstration of that concept. Look around you. Do you know how much physics is involved in your everyday playing? You are going to find out. You will also learn that it is not such a huge step to apply the physics we use here on Earth to objects and processes in the Universe.

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Natural Baking Soda Item# CDC 8410400 Environmentally safe, all-natural product cleans sinks, counters, microwaves, refrigerators, pots/pans including coffee pots, cutting boards, tubs, showers, toilets, tiles and more. Also deodorizes diaper pails, litter boxes, garbage—disposals, drains, and grease traps. Our Price \$15.42 astro101s02_gravityquiz.html Astronomy C101: Gravity Quizzes  ## Two Little Gravity Quizzes ### You and the Earth

Your weight is a measure of the force that the Earth exerts on you and that you exert on the Earth. In terms of Newton's Second Law:

F = mg

where g is the acceleration due to gravity, approximately 9.8 m/s2. In terms of the mass of the Earth, M, your mass, m, and the radius of the Earth, R (ignoring "big G"), this equation can be written as: This equation is read as the "force is proportional to the mass of the Earth times the mass of the object (you), and inversely proportional to the radius of the Earth squared." Interestingly, solid spherical bodies act as if all of their mass is concentrated right at the center! Figure out what would happen in a relative sense in the following scenarios (answers given at the end of the quiz):

1. The Earth suddenly doubles in size (radius)
1. Your weight stays the same
3. You weigh 1/4 as much
4. You weigh 1/2 as much

2. You eat so much that you now have twice as much mass (Earth stays the same)
1. You weigh twice as much
2. You weigh 4 times as much
3. You weigh the same
4. You weigh 1/2 as much

3. The Earth is now twice as massive, but your diet leaves you with only 1/2 your original mass
1. You weigh exactly the same as before the changes
2. You weigh 4 times as much
3. You weigh 1/2 as much
4. You weigh 1/4 as much

4. The Earth balloons to twice its size (radius) and also gains twice its mass
2. You weigh twice as much
3. You weigh 1/2 as much
4. You weigh 4 times as much

5. The Earth is 1/2 its current size, but twice its current mass.
2. You weigh 8 times as much
3. You weigh 1/8 as much
4. You weigh 1/4 as much ### The Sun and the Earth

We can calculate the gravitational force between the Sun and the Earth by using the mass of each object, Msun and mearth and the distance between them, D. Again, ignoring "big G," the force is represented by: Figure out what would happen in a relative sense in the following scenarios (answers given at the end of the quiz):

1. The Sun suddenly moves two times farther away
1. The force stays the same
2. The force doubles
3. The force is 1/4 as much
4. The force is 1/2 as much

2. The Sun stays in the same place, but the Earth suddenly has twice as much mass
1. The force is twice as much
2. The force is 4 times as much
3. The force is the same
4. The force is 1/2 as much

3. The Sun is now twice as massive, but the Earth has only 1/2 its original mass
1. The force is exactly the same as before the changes
2. The force is 4 times as much
3. The force is 1/2 as much
4. The force is 1/4 as much

4. The Earth moves two times farther away and also gains two times its original mass
1. The force doesn't change
2. The force is twice as much
3. The force is 1/2 as much
4. The force is 4 times as much

5. The Sun goes to 1/2 its current distance, but twice its current mass.
1. The force doesn't change
2. The force is 8 times as much
3. The force is 1/8 as much
4. The force 1/4 as much astro101s02_epe-gpe1.html

Astronomy C101: Comparison of EPE and GPE ## A Comparison of Electric Potential Energy and Gravitational Potential Energy

### Page 1 The energy levels of an electron in an atom are roughly analogous to the steps of a ladder. An electron jumping to higher energy levels can be compared to a workman climbing up a ladder. We are going to compare the energy levels of an electron in a hydrogen atom to a vertical ladder braced upon a wall. To get to a higher energy level, an electron must gain energy. It does this by absorbing a photon having exactly the right amount of energy for the jump. To climb to a higher step, the workman must use energy. He got this energy from food. There are some important differences, however. First of all, the energy levels available to an electron are not equally spaced like the steps on a ladder. They get closer together the farther away from the ground state the electron is. If this were a ladder, it would be like stepping smaller and smaller distances as one moved up. The top steps would be barely millimeters apart.  