Unit 2 (Scientific Measurement)

Question 1

Define Derived Unit, and list 3 examples

Answer 1

A unit that is defined by a combination of base units
speed m/s
volume cm^3
density g/cm^3 or g/mL

Question 2

Define volume, and explain
* the formula, AND units for rectangular shaped objects
* the conversion formula, how its measured, AND units for irregularly shaped object

Answer 2

Rectangular/cubic
* the space occupied by an object
* Equation: V = lwh
* Units: cm^3, m^3, dm^3, L, mL, etc

Irregulary shaped object
* Volume of a irregularly shaped object is measured by water displacement
* Units: mL or L
* Important Conversion: 1 cm^3 = 1mL (note this is an important conversion factor to know

Question 3

Define Density, and explain
* The equation
* The units
* What the density of water is

Answer 3

• The amount of mass per unit of volume
• Equation: density = mass/volume
• Units: g/mL or g/cm^3
• The density of water is 1.0 g/mL

Question 4

Explain Dimensional Analysis
* Definition
* What “conversion factors” are
* What the 3 base units are

Answer 4

A method used to convert units.

60 minutes = 1 hour
24 hours = 1 day
100 cm = 1m
12 in = 1ft
16 oz = 1 lb
1 inch = 2.54 cm
1 mile = 5280 ft

Mass in grams (g)
Volume in liters (L)
Length in meters (m)

Question 5

Explain the 6 major prefixes and what they mean
Mega
Kilo
Deci
Centi
Milli
Micro

Answer 5

Mega (M) - 1,000,000
Kilo (k) - 1,000
Deci (d) - 0.10
Centi (c) - 0.010
Mili (m) - 0.0010
Micro (μ) - 1x10^-6

Question 6

What’s the format for Dimensional Analysis?

Answer 6

(1.50 weeks / 1) x (7 days / 1 week) x (24 hours / 1 day) x (60 minutes / 1 hour) x (60 seconds / 1 minute) = 907000 seconds rounded

• Try to follow that format.
• On tests it has to be veritical btw
• You also need the right sig figs of course
• Remember to square or cube when necessary
• Also remember when it has multiple units to shift the numerator and demonator in the correct positions.