Day 10, Wednesday, 9 September, 2015 Chapters 1 & 2 wrap up Test on Friday Equations of Motion

Water

Test on Friday This week’s test will be a test on chapters 1 & 2 on Friday the 11 th of September. Students are expected to bring a “crib” sheet, which is a 3x5 index card with formulas and other such information on it. Answers without steps get you 0 points. There is partial credit. (If you start with the right formula that is 50% partial credit).

Things you must know for the test SI (metric system of units) Metric units Metric prefixes Multiplying or dividing dimensions changes the dimensions Length (meters) Area (meters 2 ) Volume (meters 3 ) Sig Figs Dimensional Analysis

Sig Figs Significant figures counting Measured numbers only Different uses of zero Significant figures rules Multiplication and division rules Addition and subtraction rules

Unit Analysis Algebra on the units (without numbers) Transform the given units into the answer’s units. Introduce what is not in the givens but is in the answer. Eliminate what is in the givens but not in the answer.

Average Velocity and Acceleration v avg = 1/2(v i + v f ) v avg = Δx/Δt = (x f – x i ) / (t f – t i ) a avg = Δv/Δt = (v f – v i ) / (t f – t i )

The Average of 2 numbers (# 1 + # 2 )/2

Displacement with Constant Acceleration Δx = ½(v i + v f )Δt See page 52 of the Holt text for the derivation

Final Velocity with Constant Acceleration v f = v i + aΔt See page 54 of the Holt text for the derivation

Final Velocity after any Acceleration (v f ) 2 = (v i ) 2 + 2aΔx v f = √v i 2 + 2ax See page 56 of your text for the derivation

Another Displacement with Constant Acceleration “The Equation of Motion” Displacement with Constant Acceleration Δx = x i + v i Δt + ½a(Δt) 2 This equation in a more casual form x = x 0 + v 0 t + ½at 2

The Equation of Motion in the Y dimension y = y 0 + v 0y t + ½at 2

When you solve a motion problem First: The equation of Motion x = x 0 + v 0 t + ½at 2 Second: Final Velocity v f = √v i 2 + 2ax

Some things we know Meter, m Kilogram, kg Second, s giga10 9 mega10 6 kilo10 3 centi10 -2 milli10 -3 micro10 -6 nano10 -9 pico V = v 0 + at X = x 0 + v 0 t + ½ at 2 V 2 = v a(x-x 0 )

A Lab Activity Measure your reaction time using only a ruler. Do not use a watch.

Credits