Lesson+15+&+16

**﻿Advancememt in Physics @ Dwight Englewood** **Director: Elise Burns** **TA: Sebastian Loh**

What is magnitude? same as velocity w/o direction ex: a car moving at 25 m/s North= velocity a car moving at 25 m/s= magnitude

How does magnitude relate to velocity? see above ^

How do you add and subtract vectors? media type="youtube" key="zgHTa7UK-QM" height="349" width="425" How can on object be moving in a circle at constant speed but still accelerate? How can the centripetal force for uniform circular motion alter the direction of the object without altering its speed?

How do you draw a free body diagram of circular motion?

How to solve problems directions via: physicsclassroom.com **Suggested Method of Solving Circular Motion Problems**
 * 1) From the verbal description of the physical situation, construct a free-body diagram. Represent each force by a vector arrow and label the forces according to type.
 * 2) Identify the given and the unknown information (express in terms of variables such as m=, a= , v= , etc.).
 * 3) If any of the individual forces are directed at angles to the horizontal and vertical, then use [|vector principles] to resolve such forces into horizontal and vertical components.
 * 4) Determine the magnitude of any known forces and label on the free-body diagram.(For example, if the mass is given, then the Fgrav can be determined. And as another example, if there is no vertical acceleration, then it is known that the vertical forces or force components balance, allowing for the possible determination of one or more of the individual forces in the vertical direction.)
 * 5) Use circular motion equations to determine any unknown information.(For example, if the speed and the radius are known, then the acceleration can be determined. And as another example, if the period and radius are known, then the acceleration can be determined.)
 * 6) Use the remaining information to solve for the requested information.
 * If the problem requests the value of an individual force, then use the kinematic information (R, T and v) to determine the acceleration and the Fnet ; then use the free-body diagram to solve for the individual force value.
 * If the problem requests the value of the speed or radius, then use the values of the individual forces to determine the net force and acceleration; then use the acceleration to determine the value of the speed or radius

Kepler's Law of Planetary Motion
 * 1) the path of planets are ELLIPTICAL not CIRCULAR and the sun is ine one of the focuses.
 * 2) from the center of the sun to the center of the planet it will cover equal areas in equal intervals of time. [[image:http://www.world-builders.org/lessons/less/les1/keplaws/kepler/law2.gif width="310" height="147" align="left"]]

3. 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.