PHYS16 – Lecture 2

Math ReviewFriday, September 10, 2010

Register clickers Online homework and exam Science math review Before next time

Agenda

Can you correctly answer A to this question?A) YesB) No

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http://kookaburra.com.au

Online Math Exam – Due Sunday at 11:59 pm

Online Homework for next week – Due Tuesday at 11:59 pm

Practice problems…

Online homework & exam

Read Ch. 1 in your text Significant Digits Scientific Notation Unit Analysis Vectors

Science Math Review

Digits that actually have meaning!◦ All digits in a number except for trailing or leading zeros◦ All digits that relate to the precision of the number

Examples◦ 1.001 (4 sig figs)◦ 234 (3 sig figs)◦ 900 (1 sig fig)◦ 0.005 (1 sig fig)◦ 3.4 (2 sig figs)◦ 45.6 (3 sig figs)◦ 10 (1 sig fig)◦ To write 900 and 10 with more sig figs need Sci. Not.

Math Review – Significant Digits

A way of representing a number so that you can clearly see the significant digits and the order of magnitude◦ 110 would be 1.1E2 or 1.1x102

Examples◦ 1.001 (1.001E0)◦ 234 (2.34E2)◦ 900 (9.00E2 or 9.0E2 or 9E2)◦ 0.005 (5E-3)◦ 3.4 (3.4E0)◦ 45.6 (4.56E1)◦ 10 (1.0E1 or 1E1)

Math Review – Scientific Notation

Accuracy = How close measurements are to the target

Precision = Spread in measurements

Accuracy vs. Precison

Accurate, not precise Precise, not accurate

Prefixes Conversion

◦ 1 mm = ___?___ m◦ 0.001 m◦ 1 inch = ___?___ cm◦ 2.54 cm

Solving Problems◦ Make sure answer hasthe correct units

Math Review – Unit Analysis

Ways to write Vectors◦ 3 mph to the right or 3 mph to the east◦ 5 mph at 45 degrees from x axis◦ (3,2) or

Magnitude, Direction, Components

Math Review – Vectors

yx ˆ2ˆ3

sin cos

arctan

),(

22

VVVV

V

V

VVV

VVV

yx

y

x

yx

yx

Adding Vectors◦ Break into components and add the components

Subtracting Vectors – Add the negative vector

Math Review – Vectors

)6,2(

)4,1(

)2,3(

213

2

1

VVV

V

V

)2,4()( 213 VVV

Do the Online Math Exam◦ Get the Connect Access card◦ Enter the course ID – in syllabus materials

Read Ch. 1 and Ch. 2◦ Ch. 1 won’t have any additional homework…◦ Ch. 2 online homework will be due Tuesday at

11:59 pm

Get course materials and make sure to register!

For next time…