Intro to Science

I Introduction

A. Science: from the Latin scientia, meaning knowledge. Science is finding knowledge about nature. Eg

What is the goal of science?

• The goal of Science is to understand the world around us.

• Pure Science is researching to understand the principles that control nature. This research is done for the sake of gaining more knowledge.

B. Applied Science or Technology is the practical application of science. Tech depends upon the knowledge or science learned. Science & tech are NOT all powerful; therefore, they have limitations, although, over-time, some

limitations have & may be overcome.

II. The Scientific Method

• there’s no single method to answering questions or solving problems.

• However, there is one characteristic of scientific problem solving: the logical & organized approach that’s taken: The Scientific Method

III. MEASUREMENTS IN SCIENCE

Measurement:

is the heart of science,

makes identification more precise,

allows scientific generalizations to be made.

Every measurement must have a unit

Units of Measurement:

METRIC SYSTEM : based on the #10.

INTERNATIONAL SYSTEM (SI): the modern form of the metric system of measurement

Types of Measurements

1. Length: the distance between 2 points; measured in meters (m), millimeters (mm), or centimeters (cm)

2. Mass: measure of the amount of matter in an object; measured in kilograms (kg) or grams (g)

3. Weight: measure of gravitational force on mass

4. Gravity: is an attractive force that exists among all objects; if you were on the moon, you’d weigh 1/16 th your wt on earth)

5. Time: measure of a period during which an action, process, or condition exists, continues, or occurs; measured in seconds, years, etc.

6. Temperature: measure of how hot or cold something is; measured w/a thermometer in Celsius, Fahrenheit, or Kelvin.

7. Area: the amount of surface included w/in a set of boundaries

Area= L x W (unit in cm squared); usually measured w/a ruler/meter stick

8. Volume: measure of how much space an object occupies.

a. V= L x W x H or

b. Determine the amount of water displaced by an object placed in a graduated cylinder

65.5 ml

- 50.0 ml

5.5 ml The jade has a volume of 5.5ml

Units of Measurement: LENGTH

Units of Measurement:VOLUME

A. Units of Measurement: MASS

1. Significant Figures: Since measured numbers are estimations (the last digit), there is some inaccuracy.

This inaccuracy is expressed through: SIGNIFICANT FIGURES.

Significant Figures:

• All non-zero digits are considered significant. For example, 91 has two significant digits (9 and 1), while 123.45 has five significant digits (1, 2, 3, 4 and 5).

• Zeros appearing anywhere between two non-zero digits are significant. Example: 101.12 has five significant digits: 1, 0, 1, 1 and 2.

• Trailing zeros in a number containing a decimal point are significant. For example, 12.2300 has six significant digits: 1, 2, 2, 3, 0 and 0.

Non-Significant Figures:

• Leading zeros are not significant. For example, 0.00052 has two significant digits: 5 and 2.

• The number 0.000122300 still has only six significant digits (the zeros before the 1 are not significant).

2. Scientific Notation:

• Scientific notation is simply a method for expressing, and working with, very large or very small numbers.

• It is a short hand method for writing numbers, and an easy method for calculations

• Numbers in scientific notation are made up of three parts: the coefficient, the base and the exponent

SIGNIFICANCE OF THE EXPONENT n

Scientific Notation:

EXPONENT

3. Significant Figures in Calculations: ROUNDING

• For example, 341 rounded to the nearest hundred is 300. That is because 341 is closer in value to 300 than to 400. When rounding off to the nearest dollar, $1.89 becomes $2.00, because $1.89 is closer to $2.00 than to $1.00

Rules for Rounding

• If the number you are rounding is followed by 5, 6, 7, 8, or 9, round the number up. Example: 38 rounded to the nearest ten is 40

• If the number you are rounding is followed by 0, 1, 2, 3, or 4, round the number down. Example: 33 rounded to the nearest ten is 30

Rounding fractions works exactly the same way as rounding whole numbers. The only difference is that instead of rounding to tens, hundreds, thousands, and so on, you round to tenths, hundredths, thousandths, and so on:

• 7.8199 rounded to the nearest tenth is 7.8

• 1.0621 rounded to the nearest hundredth is 1.06

• 3.8792 rounded to the nearest thousandth is 3.879

• Rule of thumb to rounding w/ decimals

5 or > you round up. Eg: 5.67 becomes 5.7

< 5 keep number as is Eg: 2.52 becomes 2.5

Significant Figures

4. In Calculations:

MULTIPLICATION and DIVISION:

5. Significant Figures In Calculations:

ADDITION and SUBTRACTION:

IMPORTANT REMINDER:

Your calculator does not know how to do significant figures. YOU must report numbers using the correct number of significant figures.

If you trust the number your calculator gives you, you might get the answer wrong!!!! TI or Casio don’t care what grade you get on the test.

Learn how to “ballpark” your answers as a guide.

Temperature Measurement: 3 ways

IV. Density

• The density of a material is defined as its mass per unit volume

• Mathematically, density is defined as mass divided by volume:

D= m/v

• EXAMPLE OF A DENSITY CALCULATION

A 20.00 mL sample of liquid is put into an empty beaker that had a mass of 31.447 g. The beaker and contained liquid were weighed and had a mass of 55.891 g. Calculate the density of the liquid in g/mL .

D= M/V

• What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL?

Keys to Problem Solving

There are seven main steps to follow when trying to solve a problem:

1. Define and Identify the Problem

2. Analyze the Problem

3. Identifying Possible Solutions

4. Selecting the Best Solutions

5. Evaluating Solutions

6. Develop an Action Plan

7. Implement the Solution