FLASH CARDS: UNITS & DIMENSIONS

Card 1

Q: What are the two parts of every measurement in physics?

A: A number (n) and a unit (u). Example: 40 cm (40 is n, cm is u).

Card 2

Q: What does “Q = n × u” mean in physics?

A: The quantity (Q) equals the number (n) times the unit (u). The unit shows what you’re measuring, the number shows how much.

Card 3

Q: Why do we need units in physics?

A: Units give meaning to numbers. Without units, “40” could mean 40 seconds, 40 dollars, or 40 elephants! Always write the unit.

FLASH CARDS: SYSTEMS OF UNITS

Card 4

Q: What is the C.G.S. system?

A: Centimeter-Gram-Second system. Length = centimeter (cm), Mass = gram (g), Time = second (s).

Card 5

Q: What is the F.P.S. system?

A: Foot-Pound-Second system. Length = foot (ft), Mass = pound (lb), Time = second (s).

Card 6

Q: What is the M.K.S. system?

A: Meter-Kilogram-Second system. Length = meter (m), Mass = kilogram (kg), Time = second (s).

Card 7

Q: What is the S.I. system?

A: International System of Units—an improved version of the M.K.S. system. It’s the global standard in science.

FLASH CARDS: FUNDAMENTAL UNITS

Card 8

Q: What are the fundamental quantities and their S.I. units?

A:

• Length: meter (m)

• Mass: kilogram (kg)

• Time: second (s)

• Electric current: ampere (A)

• Temperature: kelvin (K)

• Light intensity: candela (cd)

• Amount of substance: mole (mol)

Card 9

Q: What are “derived quantities”?

A: Quantities calculated from fundamental ones (like speed = distance/time). Their units are made from combinations of base units.

FLASH CARDS: METRIC PREFIXES

Card 10

Q: What’s the purpose of metric prefixes?

A: They show multiples or fractions of a unit (powers of ten). Example: kilometer (km) = 1,000 meters.

Card 11

Q: Match these prefixes to their powers of ten: kilo-, centi-, milli-, micro-, nano-.

A:

• kilo- (k): 10^3 = 1,000

• centi- (c): 10^{-2} = 0.01

• milli- (m): 10^{-3} = 0.001

• micro- (μ): 10^{-6} = 0.000001

• nano- (n): 10^{-9} = 0.000000001

Card 12

Q: How do you convert from kg to mg (milligrams)?

A: Move 6 decimal places right (kilo to milli: 3 for kilo, 3 for milli, total = 6).

Example: 1 kg = 1,000,000 mg

Card 13

Q: How do you convert from cm to m?

A: Move 2 decimal places left (centi to base unit).

Example: 2.3 cm = 0.023 m

FLASH CARDS: PRACTICE QUESTIONS

Card 14

Q: Which unit is used to measure mass in SI?

a) m   b) kg   c) s

A: b) kg

Card 15

Q: Which unit is used to measure time in SI?

a) m   b) kg   c) s

A: c) s

FLASH CARDS: QUICK TABLES (MENTAL MAP)

Card 16

Q: List the three main systems of units and their base units for length, mass, and time.

A:

• C.G.S.: cm, g, s

• M.K.S.: m, kg, s

• F.P.S.: ft, lb, s

Card 17

Q: List metric prefixes from largest to smallest (at least 5 each way).

A:

• Larger: exa (E), peta (P), tera (T), giga (G), mega (M), kilo (k)

• Smaller: deci (d), centi (c), milli (m), micro (μ), nano (n), pico (p), femto (f), atto (a)

CARD: VISUAL ANALOGY

Card 18

Q: What’s a great analogy for metric prefixes?

A: Think of metric prefixes like zooming in and out with a camera:

• “Kilo-” is zoomed far out (big picture, 1,000× bigger)

• “Milli-” is zoomed way in (tiny details, 1,000× smaller)

• Each “step” on the prefix map is like zooming in/out by 10×!