Announcements LAST chance to do Math Skills test is Friday (1/29) at 4:30 pm in HL G59. No class after 5pm Thursday April 1. Instead of Lab that week, Statistics Quiz. Can be taken during any scheduled lab time except after 5pm Thursday. Reminder do Pre-Lab for lab 1 Before Lab. If late to Lab (by more than 10 min) you are considered absent. Mastering Physics assignment due Monday (1/25), next due Saturday (1/30). Bring your “Student Workbook” and Homework notebook to your discussion section. Tuesdays at 4:30 pm in G59, Review the current materials using MCAT Questions.

Inclined Plane   g g Sin(  ) We effectively have a way adjust the value of g.

Rolling down the a hill  ff   l=3m Ignore change in direction a=g Sin   x=3m/Cos(  ) a=g Sin  a=0  ff

Rolling up hill  f  00   Ignore change in direction a=g Sin  l  xCos(  )=0.38m a=g Sin  a=0 00  f  h  xSin(  )=0.27m

Recall 9m 6m A B A B What can we through ball A down such that it will hit the ground at the same time at ball B? So if I through ball A down (-) with an initial speed of 2.67m/s, ball A will hit the ground at the same time as ball B.

Graphically Velocities are not the same because v A0 ≠0. Slope are the same because a=g are the same.

What about Can we through ball B such that it will hit the ground at the same time at ball A? 9m 6m A B A BSo if I through ball B up (+) with an initial speed of 2.17m/s, ball B will hit the ground at the same time as ball A.

Graphically Velocities are not the same because v A0 ≠0. Slope are the same because a=g are the same. By throwing the ball upwards we can delay its impact time with the ground.

General Relations Near the earth’s surface Gravity is just a constant acceleration a=g=9.8m/s 2 Down (it is a vector).

Scalars, Vectors, Tensors Scalar (A measurable quantity describable by a singular number) –Temperature, length, speed, brightness, time, pressure, volume, area, energy,…. Vector (A measurable quantity describable by a one or more numbers including a direction of some sort). –Position, velocity, acceleration, force, momentum, color, a row or column of numbers, electric field, magnetic field, some sets of functions, …. Tensor (More complicated mathematical structure). –Matrix, spinners, ….

Vectors Vectors are things which obey the algebra of vectors. (a lot of help) A Vector must have a magnitude and a direction. Vectors Commute Vector AdditionVector Scalar (dot) product Vectors Distributive Magnitude of a Vector

Vector times a scalar Some Vector examples

More on Vectors scalar product  Vector Scalar (dot) product Vectors Distributive

Unit Vectors A vector whose magnitude =1. Orthogonal unit vectors

Completing the Algebra Vector, Cross,Product Does not commute Will better define and use later