Review Session #1Uncertainty, Sig Figs, & UnitsMINNETONKA HIGH SCHOOL | PHYSICS

Systems and Units

Length

Mass

Time

Electric Current

Temperature

Amount of Substance

Luminous Intensity

Fundamental S.I. Units:

What are the SI base units for…

N

Pa

J

Example IB Question

Types of Error

RandomError

SystematicError

Example IB Question

Three ways to Report

AbsoluteUncertainty

Δy

Fractional Uncertainty

Δy/y

PercentageUncertainty

Δy/y ×100%

Other General Rules

Your uncertainty should typically only have one significant digit (two are okay in some situations)

Your precision in the measurement and uncertainty MUST match

Warm Up IB Question

Uncertainty in Calculations

Adding or Subtracting

If y = a ± b then Δy = Δa + Δb

To find the uncertainty in a sum or difference you just add the uncertainties of all the ingredients.

Try This

A 9.51 0.15 meter rope ladder is hung from a roof that is 12.56 0.07 meters above the ground. How far is the bottom of the ladder from the ground?

Uncertainty in Calculations

Multiplying or Dividing

If y = a × b ÷ c then Δy/y = Δa/a + Δb/b + Δc/c

To find the uncertainty in a product or quotient you just add the percentage or fractional uncertainties of all the ingredients.

Try This

A car travels 64.7 0.5 meters in 8.65 0.05 seconds. What is its speed?

This is in the Data Booklet ☺

Example IB Question

Example IB Questions

Rules for Zeros in Significant Digits

1. All zeros between non-zero digits are significant

2. Filler zeros to the left of an understood decimal place are not significant.

3. Filler zeros to the right of a decimal place are not significant.

4. All non-filler zeros to the right of a decimal place are significant.

Math with Sig Figs – [× & ÷]

Multiplication and division – round your answer to the same number of significant digits as the quantity with the fewest number of significant digits.

(1.2 cm)(2 cm) =

π(2.75 cm)2 =

5.350 m / 2.752 s =

(0.0075 N)(6 m) =

Math with Sig Figs – [+ & -]

Addition and subtraction – round your answer to the same number of decimal places as the quantity with the fewest number of decimal places.

1.2 cm + 2 cm =

2000 m + 2.1 m =

0.00530 m – 2.10 m =

5.23 mm + 3.1256 mm =

Mixed Practice

56.20 cm + 2.000 cm =

(206 m)(1200 m) =

10.500 km – 0.08 km =

(5708 m)(0.0034) =

367 m / 2.1 s =

892.2 m2 + (78 m)(31.2 m) =

Testing Tips | Paper 1

• Answer EVERY question!!!!• The topics are in the same order as your

data booklet• Eliminate answers where you can• No calculator so the data booklet will help

but can’t serve as a crutch

Testing Tips | Paper 2

• Budget your time wisely• Definitions related to formulas (usually

ratios) can be expressed using the formula• Pay attention to the value of each question,

the higher the value, they more they want• Round answers to 3 sig figs unless it’s weird• Multi-step problems usually give you an in

Testing Tips | Paper 3

• Complete Section A and Option D• Use your time wisely• Sig figs matter when they say they do• You can study for this one in a more

focused way because you know the topics