Ch5_hwangt

= Chapter 5 =

Circular Motion and Satellite Motion:Lesson 1
toc Object moving in a uniform circular motion have a changing velocity but moves in constant speed. The velocity and speed are calculated in the same way by using hte equation 2 time pi times the radius all over the period. These two are different because velocity is a vector and speed is a scalar. Because velocity is a vector, direction is also taken into account so since the direction is always changing when moving in a circular motion, the velocity is constantly changing.
 * A)**__Speed and Velocity. Are they the same or different?__

Because an object has constant speed when moving in a uniform circular motion, many people believe that there is no acceleration but they are sadly mistaken. Because acceleration is a vector unit, the acceleration is always changing. This is because the direction of the object is always changing so there will always be acceleration. To find average acceleration, one can use the equation of the change in velocity over the time.
 * B)**__The Details on Acceleration__

Centripetal force is the force in a system that points toward the center of the circle. In circular motion, there must be a constant force allowing for the object to continue changing its velocity. Because of inertia, people perceive that the force is outward when in reality it is inward. This centripetal force that enables objects to keep moving in a circular path.
 * C)**__The Requirements of Centripetal Force__

Centrifugal means away from the circle or outside the circle. One must never use this word when dealing with physics because it does not exist. A person feels like he or she is being pulled outward because of inertia.
 * D)**__It Has Nothing To Do With Circular Motion!!__

In circular motion problems, the three important quantities are speed, acceleration, and force. Average speed is calculated from the equation 2 time pi time the radius all over the period, acceleration is calculated 4 time pi squared time the radius all over time squared or velocity squared over the radius, and net force is calculated by multiplying the mass times the acceleration.
 * E)**__Math Makes Circular Motion Problems Easier__

Circular Motion and Satellite Motion:Lesson 2 (Method 5)
In class, we have solved problems for net force by using the equation F=ma but have not applied it to circular motion yet. In order to apply it to circular motion, the acceleration is changed to v 2 /R which is what acceleration equal when dealing with circular motion problems. The acceleration of an object moving in circular motion is directly proportional to the net force and inversely proportional to the mass of the object.
 * A)**__Newton's Law and Circular Motion__

There are three different parts of a ride that uses centripetal force clothoid loops, small dips and hills, and banked turns. In a loop, speed and direction changes when going up and down (slower at the top), so the centripetal force changes. One feels as if they weigh more at the bottom of the loop because the normal force increases.
 * B)**__The Physics Behind Amusement Parks and Roller Coasters__

Problems dealing with circles are found in athletics as well because of the turns that are made. These turns are part of a circle. When a person turns on a horizontal surface they tend to lean in which creates multiple components. The constant force balanced the downward force of gravity and meets the centripetal force requirement for an object in uniform circular motion.
 * C)**__The Physics Behind Athletics__

Circular Motion and Satellite Motion:Lesson 3 (Method 5)
Gravity is the name of the force that keep objects that are near it or on it from floating away. Gravity is what keeps us on the Earth and is why things come down then they are in the air. The acceleration of gravity is 9.8 /s 2.
 * A)**__More Than Just A Name__


 * B)**__Kelper's 3 Laws of Planetary Motion__
 * The paths of the planets about the sun are elliptical in shape, with the center of the sun being located at one focus. (The Law of Ellipses)
 * An imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time. (The Law of Equal Areas)
 * The ratio of the squares of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun. (The Law of Harmonies)

The relationship between gravity between the Earth and any other object and the distance that separates their centers. Gravity between two objects is proportional to 1/d 2
 * C)**__Universal Gravitation__

It is not only gravity on earth, but the universality of gravity. It states that all objects attract each other with a force a of gravitational attraction.
 * D)**__Cavendish and the Value of G__

It gives a constant to the proportionality that the product of the masses over the squared distance of the objects is proportional to the force of gravity between the objects. The constant makes this proportion into an equation.
 * E)**__G__



Cavendish historical context of finding G.

How does g change with location? It decreases as you get further from the surface of the earth.

The Clockwork Universe Lesson 2 (Method 1)
Topic Sentence: Using the previous workings of Copernicus, Galileo, and Kepler, Newton discovered that gravity is universal, and caused planets to orbit the sun in imperfect, elliptical orbits.
 * Nicolaus Copernicus thought of the heliocentric idea of the universe, which stated that the Earth revolved around the Sun.
 * Galileo continued his ideas, which caused debate in the Catholic church.
 * Johannes Kepler modified Copernicus's ideas based on observational data.
 * Kepler said that the planets orbited the sun in ellipses, based on observations
 * He did not know why, but thought that it may be due to magnetic influence from the sun.
 * Coordinate Geometry: represents geometrical shapes by equations, and combines/rearranges such equations to establish other geometrical truths.
 * Newton then followed up on the work, and focused on deviation from steady motion, and why.
 * He created a quantitative link between force and deviation from steady motion.
 * Newton thought that gravity was universal and worked for the whole universe,was able to show mathematically that planets orbit the sun in ellipses due to gravity, and predicted that gravity between the planets would cause small changes from the actual elliptical paths.
 * Pierre Simon Laplace studied mechanics (the study of force and motion).
 * Determinism: the fact that the universe worked like a clock, and was entirely predictable.

Circular Motion and Satellite Motion:Lesson 4
- They were added onto by Newton later - The Law of Ellipses: the path of the planets about the sun is in elliptical shape, with the center of the sun being located at one focus. - The Law of Equal Areas: an imaginary line drawn from the center of the sun to the center of the planet will sweep out equal areas in equal intervals of time - The Law of Harmonies: the ratio of the squares of of the periods of any two planets is equal to the ratio of the cubes of their average distances from the sun - A satellite is any object that is orbiting the earth, sun, or any other massive body - It can be either natural or man made - They move in an orbit - They act similarly to projectiles as gravity is the single force acting upon it - The motion of satellites can be described by its' acceleration and velocity - These two components are constantly changing - Satellites also move in an elliptical motion - The final equation for velocity of a satellite moving about a central body in circular motion is:
 * A)**Kepler was known for creating three different laws
 * B)**What are circular motion principles for satellites?
 * C)**Where does mathematics come into satellite motion?

After taking notes on this lesson, I explained what I learned to a friend from another town who is learning the same thing but had trouble understanding. We mainly talked about how mathematics came into play and how it could be applied to real life situations. **D)**What is weightlessness and how does it apply to the situation? - Sensations are the same for both astronauts and regular people on a roller-coaster  - Additionally, the causes for these sensations are the same as well  - Weightlessness is simply a sensation experienced by an individual when there are no external objects touching one's body and exerting a push or a pull on it  - Weightlessness is ONLY a sensation  - It has very little to do with weight and mostly to do with the presence or absence of contact forces  - In addition, a scale does not actually measure one's weight  - Earth-orbiting astronauts are weightless because there is no external contact force pushing or pulling on their body  - There are many misconceptions concerning this concept - The orbits of satellites about a central massive body can be described as either circular or elliptical - There is no acceleration in the tangential direction and the satellite remains in circular motion a constant speed - A satellite orbiting the earth in elliptical motion will experience a component of force in the same or the opposite direction as its motion - This force is capable of doing work upon the satellite, thus, the force is capable of speeding up or slowing down the satellite - Work-energy theorem- the initial amount of total mechanical energy of a system plus the work done by external forces on that system is equal to the final amount of total mechanical energy of the system - The mechanical energy can be either in the form of potential energy or kinetic energy - A work energy bar chart represents the energy of an object by means of a vertical bar - A satellite orbiting in elliptical motion will speed up as its height or distance of from the earth is decreasing and will slow down as they both are decreasing
 * E) ** What are energy relationships for satellites?