Which of the measureable factors in your pendulum is

most precise? Least precise? How can you tell?

Take 15 minutes to finish collecting data for your 2nd page

pendulum lab

Significance

• Why do we use significant figures?

• Period: 1.235, 1.175, 1.443, 1.336

• Avg = 1.29725

Significance

• Why do we use significant figures?

• Period: 1.235, 1.175, 1.443, 1.336

• Avg = 1.29725

• Really?!?!?

• How about 1.3

Significance

• Why do we use significant figures?

• Period: 1.300, 1.301, 1.301, 1.301

• Avg = 1.30075

• 1.301

Rules for significant figures

• All non-zero numbers are significant

• 2.3563

• 24456

• 84323445

Rules for significant figures

• All trapped zeros are significant (in between other significant numbers)

• 2.30563

• 204456

• 843234405

Rules for significant figures

• All leading zeros are not significant

• 0.00000230563

• 204456

• 0.0000843234405

Rules for significant figures

• zeros at the end are significant only if there is a decimal point

• 2.3563000 - yes

• 24456000 - no

• 843234450000.0 - yes

Please take out your homework.

• Warm-up:

• Make a guess (based on your data) how long it will take for my 3 m long pendulum to complete one period.

• Write down 20 different units of measure

Rules for significant figures• Adding and subtracting, use the least significant

digit:

• 2.3546

• +1.5

• 3.8546 ->3.9

• 0.135

• +2.55489

• 2.68989 -> 2.690

Rules for significant figures• Multiplying and dividing, use the least number of

significant digits:

• 2.3546 (5 significant digits)

• +1.5 (2 significant digits)• 3.5319 ->3.5 (answer has 2)

• 0.135 (3 significant digits)

• +2.55489 (6 significant digits)

• 0.34491015 -> 0.345 (3 significant digits)

Add the following distances using correct significant figures

3.45 m + 9.82 m + 13.653 m + 0.23 m

Multiply the following distances using correct significant figures

(3.45 m)(9.82 m )(13.653 m )(0.23 m)

Scientific Notation

Scientific Notation

Most numbers are really annoying

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

380

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

38000

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

38000000

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

380000000

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

380000000 m

How big is an atom?

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

380000000 m

How big is an atom?

0.000

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

380000000 m

How big is an atom?

0.00000

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

380000000 m

How big is an atom?

0.0000000

Scientific Notation

Most numbers are really annoying

How many meters is it to the moon?

380000000 m

How big is an atom?

0.0000000001 m

Scientific Notation

Let’s write those in a not annoying way.

380000000 m

Scientific Notation

Let’s write those in a not annoying way.

380000000 m x 101

Scientific Notation

Let’s write those in a not annoying way.

380000000 m x 102

Scientific Notation

Let’s write those in a not annoying way.

380000000 m x 108

Scientific Notation

Let’s write those in a not annoying way.

380000000 m x 108

Check our sig figs, though…

Scientific Notation

Let’s write those in a not annoying way.

38 m x 108

Check our sig figs, though…

Scientific Notation

Let’s write those in a not annoying way.

00000000001 x 100

Scientific Notation

Let’s write those in a not annoying way.

00000000001 x 10-10

Scientific Notation

Let’s write those in a not annoying way.

00000000001 x 10-10

Check our sig figs again

Scientific Notation

Let’s write those in a not annoying way.

1 x 10-10

Check our sig figs again

Units

• Length – meter – m

Units

• Length – meter – m

• Time – second – s

Units

• Length – meter – m

• Time – second – s

• Temperature – Kelvin – K

Units

• Length – meter – m

• Time – second – s

• Temperature – Kelvin – K

• Mass – kilogram – kg

Units

• Length – meter – m

• Time – second – s

• Temperature – Kelvin – K

• Mass – kilogram – kg

• Electric current – Ampere – A

• Amount – mole – m

• Luminous intensity – Lumen - L