Intro to Physics Math Skills Review Ms Denzmores

Intro to Physics & Math Skills Review Ms. Denzmore’s Physics Class De. Bakey HSHP

What is physics? �Physics is the study of the physical world. �Consequently, there are many areas within physics…

My favorite area! Astrophysics: The physics of stars, galaxies, etc

Who needs math? �YOU NEED MATH! �In order to do well in physics, you’ll need to be proficient in algebra and some trigonometry and geometry �Let’s review some basic info

Scientific Notation �Why do we use scientific notation? �To make very big and/or very small numbers easier to handle �What is the average distance between the Sun and the Earth? � 93, 000 miles or 9. 3 x 107 miles �What is the average distance between the Sun and Pluto? � 3, 670, 052, 070 miles or 3. 67 x 109 miles

How to write a number in scientific notation. � 1. Put the decimal after the first non zero digit and drop the zeroes i. e. 93, 000 becomes 9. 3 � 2. Multiply the coefficient by 10 i. e. 9. 3 x 10 � 3. To find the exponent, count the number of places from the decimal to the end of the number i. e. 9. 3 x 107

Multiplying #s in Scientific Notation Rules for multiplication: � 1) Multiply the coefficients � 2) Add the exponents (base 10 remains !!!) �Examples: �(3 x 104)(2 x 105)= 6 x 109 �(5 x 103)(6 x 103)= 30 x 106 = 3. 0 x 107 �(3 x 10 -3)= 9 x 10 -6

Dividing #s in Scientific Notation �Rules for division � 1) Divide the coefficients � 2) Subtract the exponents (base 10 remains) �Examples: (6 x 105)/(2 x 102)= 3 x 103 (8 x 10 -6)/(4 x 10 -3)= 2 x 10 -3 (2 x 103)/(4 x 10 -8)= 0. 5 x 1011 = 5 x 1010

Significant Figures Rules for determining sig figs: � 1. All non-zero digits are significant � 2. Leading zeros in decimal numbers are not �significant � 3. Zeros between nonzero numbers are significant � 4. Trailing zeros in numbers without decimals are not significant. . . but if the number has a decimal, trailing zeros are significant.

How many sig figs? ? Example 1: 38. 15 cm Answer: 4 sig figs Example 4: 50. 8 mm Answer: 3 sig figs Example 2: 0. 008 mm Answer: 1 sig fig Example 5: 25, 000 years Answer: 2 sig figs Example 3: 0. 0156 oz Answer: 3 sig figs

Significant Rules When multiplying or dividing, the answer can only show as many significant digits as the measurement showing the least number of significant digits Example: 2. 05 x 3. 110 x 0. 0020 = 0. 12751 Answer: 0. 13

Significant Rules �When adding or subtracting, the answer can only show as many decimal places as the measurement having the fewest number of decimal places �Example: 2. 115 + 0. 0024200 + 000. 41 = 2. 52742 �Answer: 2. 53

Mars Climate Orbiter �Spacecraft launched in 1999 �NASA lost contact with it 9 months later �Investigation revealed that it burned up in the Martian atmostphere �Cost: $193 million �What happened?

It was the units!! �UNITS MATTER!! �If you don’t use the correct units, your answer will be wrong. �In physics, we use the metric system �Mass (kilograms: kg) �Time (seconds: s) �Length (meters: m)

Metric powers of ten

The ones you must memorize!

Examples �How many Hz are in 3250 GHz? �G is Giga (109) � 3250 GHz x 109 Hz 1 GHz 3. 25 x 1012 Hz �How many km are in 225 mm? � 225 mm x 10 -3 m x 1 km 1 mm 10 3 m Or � 225 mm x 1 km 1000 m 2. 25 x 10 -4 km

Be careful…some are tricky! �How many cm 2 are in 400 m 2? �When you have squared and cubic units, you must square or cube your conversion factors!! � 400 m 2 x ( 1 cm) 2 = 400 x 1 cm 2 = 4 x 106 cm 2 (10 -2 m) 2 10 -4

Another example �How many cm 3 are in 625 km 3 ?