Chapter 2
Measurement
Quantitative (definite form, ie. numbers) vs. Qualitative Measurement (description)
--science tends to expect exact numbers—quantitative
This child has a temperature of 1020F vs. This child feels hot.
System of Measurement—Metric System
The International System of Units - SI
Quantity Unit Symbol Instrument
Length Meter m, cm, mm, km Ruler, Meter Stick
Volume Liter L, mL Graduated Cylinder
Meter 3 m3, cm3, mm3 Ruler, L*W*H
Mass Gram g, kg, mg Scale (triple beam balance)
Interesting fact:
1 cm3 of water = 1 mL of water = 1 gram of water (at 3.980C)
Metric System Increments (in multiples of 10)
Kilo 1000 times 1000 times bigger
Deci 1/10 th 10 times smaller
Centi 1/100 th 100 times smaller
Milli 1/1000 th 1000 times smaller
Micro 1/1,000,000 1,000,000 times smaller (million)
Nano 1/1,000,000,000 1,000,000,000 times smaller (billion)
Distance
Direct measurement of distance
Computed measurement for area (Computed measurement for volume)
Volume
Direct measurement of volume using a graduated cylinder
Used to measure liquids
Used to measure granulated solids
Meniscus-lowest point of the curve at the top of a liquid
you read the lowest point of the liquid in the graduated cylinder
Volume – continued
Calculated volume using a ruler length X Width X Height
Used for regularly shaped objects: cubes, etc
Units in meter cubed
Calculated volume using Water displacement
Used to measure irregularly shaped objects
Amount of water + object = ______mL
Amount of water before = - ______mL
Volume of object = ______mL
Density
Story of the king’s crown—was it gold or was it fake? Archimides
Problem: I have a lump of yellowish, metallic looking stuff; how do I figure out what it is?
1. Weigh it Mass 10g
2. Volume Water displacement 100mL
3. Density D=M/V 10g/100mL= .1g/mL
4. Look it up
Density is the ratio of the mass to the volume of an object
Units for density g/mL or g/cm3
Density is a PHYSICAL PROPERTY that doesn’t change for any one element
Formula for density:
D=M/V M=D*V V=M/D