Physical Science

Transcript Physical Science

Physical Science Ch. 1 Part II

Physical Science Methods

SI System of Measurement

 The SI system is a base ten system of measurement. All units are either multiples of 10, or decimals. It is also know as the metric system Prefixes added to root words will tell you what multiple a measurement is.

For example........

• Centi- = 1/100 or .01 1 meter = 100 cm • Milli- = 1/1,000 or .001 1 meter = 1,000 mm • Kilo- = 1,000X 1,000 meters = 1 km

How Familiar Are You with Units of Measurement?

 10 km is about how far in miles?

 A person who has a mass of 75 kg weighs about how much in pounds.

 About how much is a quart, and how many quarts are in a 2 liter bottle?



10 km = 6.2 miles



75 kg = 165 pounds



2 liters = 2.12 quarts

• If a long-jumper goes 7.255 m, is that good or bad?

• The speed limit says 104 km/hr. How fast is that?

• The sumo wrestler weighed 228 kg. How heavy is that?

Standards

 A standard is an exact quantity used for comparison.

There are 2 commonly used systems of measurement. The

SI system

(worldwide) and

English

units (primarily in the U.S.).

 How many cubits from one side of the room to the other?

• Why do you think the U.S. does not use the SI system as much as the rest of the world?

• What are some SI units which we see commonly used in the U.S.?

• Why do you think that Coke is measured in liters, while milk is usually measured in English units (quarts or gallons)?

Time • Time is the interval between two events, and is the only measurement which uses the same units (seconds) for both SI and English measurements.

• Why do you think time has the same SI and English units of measurement?

Length

 Length is a measure of the

distance

between 2 points.

 The SI unit for length is the meter (m).

• The lead in a mechanical pencil is usually measured in millimeters (mm), referring to it’s width.

• Why do you think this is done in mm?

Mass • Mass is a measure of the amount of matter in an object.

All

objects have mass.

The SI unit for mass is the kilogram (kg).

Mass is measured using a balance (not a scale.).

• If the 2 balloons are the same size, which one has a greater mass?

• As you prepare to go scuba diving, you have 2 tanks, one full of compressed air and the other one empty. If you threw them both into the water, which one would float higher in the water and why?

• The formula for mass is Mass = Density x Volume We'll use this formula later on.

Also, 1 kg = 2.2 pounds

 The steel cube and the wooden block have different masses, even if they're the same size.

Is mass the same as weight?

Explain.

Volume

 Volume is the amount of space occupied by an object (how big it is).

 For a regularly shaped object (square or rectangular) volume is measured in cm 3 .

The formula is length x width x height.

• What is the volume of the object shown below?

• If you have an object that is not a perfect square or rectangle, how do you think you could find it's volume?

• The best way to find the volume of an irregularly shaped object is through water displacement.

Density

• Density is the amount of mass an object or material has, based on it's volume.

For example, if I have 2 objects the exact same size, the one with more matter in it is denser.

Like a bowling ball and a volleyball.

• Some examples of objects or materials where density is important: -a snowball -liquid mercury -humans floating and/or sinking -a lead sinker -warm and cold air

 The formula for density is mass divided by volume.

If mass is measured in grams and volume is measured in cm 3 , the mass/density would result in the label being g/ cm 3 .

Water for example has a density of 1 g/ cm 3 .

The Dead Sea

Triangle Formulas

Based on the diagram of the unknown metal block below, identify the metal from the following list: (note: the block has a mass of 480 g) A. Steel (density = 3 g/cm 3 ) B. Iron (density = 3.8 g/cm 3 ) C. Aluminum (density = 2 g/cm 3 )

• Bud is out on the lake fishing last spring He accidentally spilled his cooler into the water as he was putting it on the boat. He was able to retrieve all of the cans of Diet Coke because they floated, but the cans of regular Coke sank. Why do you think this happened?

• Bud went fishing again in the middle of the summer, and once again spilled his cooler of Coke and Diet Coke. This time, however, all of the cans sank?

What’s up with that? Hmmmm…….

Derived Units

 Units which are a combination of other units are called derived units.

 Ex.: cm 3 for volume, mi/hr for speed

1. Convert room temperature (72 F) to: A. Celsius B. Kelvin 2. A brick has a height of 8 cm, width of 12 cm, and length of 20 cm. What is it’s volume?

If the brick in problem #2 has a mass of 3840 g, what is it’s density?

4. Will the brick float or sink in water? Explain why.

5. A beaker has 235 mL of water in it. When a flashlight battery is dropped in, the water level rises to 485 mL. What is the volume of the battery?

6. If the battery in problem #5 has a density 1.5 g/cm3, what is the mass of the battery?

1. Convert 450 cm to: A) Km B) mm 2. If the melting point of lead is 327 degrees Celsius, what is it in: A) degrees Fahrenheit B) Kelvins 3. An unknown metal has a volume of 5 cm 3 and a mass of 13.5 g. Using the table on pg. 19, identify this metal.

Graphing

 A graph is a visual display of information or data.

Graphs often show patterns or relationships in the data, and may be used to predict future results.

Types of Graphs

 There are 3 main types of graphs: 1. Line graph - shows trends or patterns over time, usually with larger numbers 2. Bar graph - compares smaller values which are usually counted 3. Circle (pie) graph - shows 1 fixed quantity broken down into parts (usually percentages)

Line Graphs

• Line graphs use an X axis (horizontal) and a Y axis (vertical) to plot data points, which are then connected with either a straight or curving line.

• The data measured on the X axis is the independent variable, and the Y axis shows the dependent variable.

The graph below shows how long students had to wait while registering for school this past month.

• What does the graph show you?

• Hypothesize as to why Monday and Friday had the longest wait times.

Bar Graph

• A bar graph is very similar to a line graph, just with smaller numbers. • Also, a bar graph shows information, but may or may not show any patterns or trends.

For example........

Circle Graphs

• Circle graphs are best at showing percentages.

• Examples of information you may see on a circle graph include......

Opinion Polls

Do you favor or oppose Initiative and Referendum?

Election results

2004 Presidential Election

3% 1% 3% 46% 47% Bush Kerry Nader Sharpton Other

Financial Information

Dollar Breakdown of Expenses in the Pleasant Hill School District

Salaries-41 cents Facilities-29 cents Textbooks-16 cents Supplies-9 cents Other-5 cents

• The hottest temperature ever recorded in Missouri was 119 degrees Fahrenheit on Aug. 14, 1938. Convert this to Celsius and Kelvins.

• The density of clay is 1.4 g/cm 3 . If a lump of clay has a mass of 28 g, what is it’s volume?

• A rock with a density of 2.8 g/cm 3 and a mass of 112 g is dropped into a graduated cylinder with 50 mL of water in it. What will the water level rise to?

• What would be the combined mass of the water and the rock in the graduated cylinder?

• An old car is taken to the junkyard where it is placed in the crusher. Tell how the following properties changed, if at all.

• Volume • Mass • Weight • Density

• On a hot August day, Bill wants to go fishing for muskie. So he calls his friend Roland who tells him, “Boy, don’t you know that muskie won’t bite if the water temperature is over 80 degrees” “Trust me” said Bill, “there’s a way around that”.

What was Bill’s secret?

The marshmallows shown are placed in a food sealer, and then all the air is sucked out of the container. With no air pressure acting on them, the marshmallows expand. What effect does this have on the marshmallow’s: A. Mass B. Weight C. Volume D. Density

Apu notices that some of the dairy products in his cooler at the Kwik-E-Mart are turning bad before the expiration date. He decides to check the temperature of his cooler to see if that is the problem.

Does it matter where he places his thermometer in the cooler? Explain.

• Kim bought a loaf of bread at the store, and was upset to find that the bagger had crushed the bread by placing it at the bottom of the bag.

Tell what happened to each of the following as the bread got crushed: Mass, Density, and Volume • Also, what is the relationship between the volume and density of the loaf of bread?

Outcome of 1 Die Rolled 100 Times

18 16 14 12 10 8 6 4 2 0 1 2 3 4 5 6 Single Die

Outcome of 2 Dice Rolled 100 Times

16 14 12 10 8 6 4 2 0 2 3 4 5 6 7 8 9 10 11 12 2 Dice

1. Tell which is the X and Y axis,

and

X – tell which variable goes on each.

horizontal, independent variable

Y –

vertical, dependent variable

2. Give the term which describes each of the following definitions: A. The amount of matter in an object B. The amount of space occupied by an object C. The SI unit for temperature D. An SI unit used for liquid volume – E. 0 Kelvins – 3. A rectangularly shaped object is 4 cm high and 2 cm wide. If the object has a mass of 72 g and a density of 3 g/cm3, what is the volume of the object?

Volume = 4. Convert 112 degrees Celsius to degrees Fahrenheit and Kelvins.

Degrees Fahrenheit =

233.6

Kelvins =

385

1. A rectangularly shaped object is 4 cm high and 2 cm wide. If the object has a mass of 96 g and a density of 3 g/cm3, what is the volume of the object?

Volume = 2. Tell which is the X and Y axis,