# Unit 1 Using SI Units.

## Presentation on theme: "Unit 1 Using SI Units."— Presentation transcript:

Unit 1 Using SI Units

Measurement Standard An exact quantity that people agree to use for comparison. * helps you get the same answer as other people

What was used as the earliest measurement standards?
Body Parts * The question then, is WHO’S body parts? The KING’S or QUEEN’S

Is your hand or a body part a good standard of measurement?
* no * people’s hands are not the same size * get different answers

In order for any measurement to MAKE SENSE; two things must be included.
1.) a number 2.) a unit

Every type of measurement has a base or central unit.
* meter (distance or length) * liter (volume) * gram (mass) * second (time)

Adding a prefix to a base (central) unit, you can create a whole new unit to measure any object.

Prefixes Used When Measuring:
Large Objects kilo = 103 hecto = 102 deka = 101 Small Objects deci = 10-1 centi = 10-2 milli = 10-3

Length Mass Temperature Time Area Volume Density Weight

Length The distance between two points. Base (central) units of length
* (US) FOOT [ft] * (SI) METER [m]

Length Length of an object or the distance between two points is measured using a METERSTICK.

Mass “A body of coherent matter.”
* a collection of stuff joined to form an object Base (central) units of mass * (US) SLUG [slug] * (SI) KILOGRAM [kg] sometimes gram [g]

Mass Mass is measured using a BALANCE.

Measurement of how hot or cold something is.
Temperature Measurement of how hot or cold something is.

Temperature Base (central) units of temperature * (US) FAHRENHEIT [oF]
* (SI) CELCIUS [oC] > (SI) KELVIN [K] * this is an absolute scale

Temperature Temperature is measured using a THERMOMETER.

Absolute Zero The coldest possible temperature.
* temperature where ALL motion stops * 0 Kelvin * found by the formula: K = oC

Time Interval between two events. Base (central) units of time
* (US) SECOND [s] * (SI) SECOND [s]

Time Time can be measured using a CLOCK or a CALENDAR.

Derived Units Obtained by combining multiple units of measurement.

Area The amount of surface included in a set of boundaries.
Found by the formula: * Area = length x width

Area What is the difference between length and width? DIRECTION

Area Base units of area * (US) FEET SQUARED [ft2]
* (SI) METERS SQUARED[m2]

Volume The amount of space an object occupies.
Easy with liquids & gases, harder with solids * for a solid you may need the formula: volume = l x w x h

Volume For a liquid or a gas all you need is a devise that is designed to measure volume. * a beaker, a flask or a graduated cylinder

Volume Base (central) units of volume * (US) GALLON [gal]
* (SI) LITER [L] sometimes centimeters cubed [cm3]

Volume 1 milliliter equals 1 centimeter cubed. * 1 mL = 1 cm3

Density The measurement of how thick, compact and solid an object is.
Relationship between the mass & volume of an object

Density Found by the formula: * Density = mass ÷ volume
Expressed in g/L or g/cm3 * a mass unit / a volume unit

Weight Measurement of the force of gravity pulling on the mass of an object. Changes as gravity changes. Base units of weight * (US) POUND [lb] * (SI) NEWTON [N]

Weight Weight is measured using a SPRING SCALE.

MASS and WEIGHT are NOT the same thing!

(changing a physical property does NOT change the substance)
Physical Properties Characteristics of a substance that can be used to identify it. Color Shape Texture State of matter Size All measurements (changing a physical property does NOT change the substance)

The End