Did you do as well as you should have, given how much you prepared?

1. Did you do as well as you should have, given how much you prepared? • Yes • No

2. Quiz question 1a asked to convert a value in mg to a value in kg. The value of mg is • 1/10 g • 1/100 g • 1/1000 g • 1/1000 kg • 10 g • 100 g • 1000 g • 1000 kg • Other

3. 14 of 40 Expressing 2.8 mg in kg. What factor(s) will be involved? • 1000, for milli • 1000, for kilo • 1/1000, for milli • 1/1000, for kilo • Both 1 and 2 • Both 3 and 4 • A different pair of these • None of the above.

4. The best choice is - ‘None of the above’. In ANY unit conversion, the factor to apply is 1, or sometimes 1 x 1, or 1 x 1 x 1, etc.

5. 15 of 40 Is mg smaller than kg, or larger? • Smaller • Larger • Same size • Didn’t learn that • Can’t remember

6. 11 of 40 Since mg is smaller, the number part of the value in kg will be • Smaller • Larger • Can’t tell • Afraid to guess

7. Did you think about this at quiz time? • Yes • No

8. An ordinary-size number with a small unit means a small quantity. The same quantity using a large unit must be still a small quantity. Hence the number part that goes with the large unit must be VERY small. SIMILAR THINKING will let you CATCH MISTAKES where you have a conversion factor backward.

9. 2.8 mg in kg? 2.8 mg x ( 1 g / 1000 mg ) x ( 1 kg / 1000 g ) = 2.8 x 10-6 kg Another note: The value of a prefix does NOT express it in terms of the unit you start with. The prefix relates the unit to the base unit. Hence the TWO factors above: one to remove mg, leaving g, one to obtain kg.

10. 13 of 40 1b requires expressing 0.37 kJ in MJ. Do you need to know anything about what J is? • Yes • No • Abstain

11. No. Since both the given quantity and the required unit use metric prefixes with the same symbol, all you need to know is that J is something which metric prefixes work with. Some points of etiquette: Except for the original m, g, and s, almost all metric base units come from the name of a scientist. Hence the SYMBOLS for such units are ALWAYS capitalized. The NAMES of the units, when spelled out, are NOT capitalized. (Thus, N for newton, but neither n nor Newton, when referring to the unit.) Further, unit symbols do NOT use periods; they are symbols, not abbreviations. (But a period will follow a symbol anyway if it is the end of a sentence.)

12. How big is the answer's number, compared to the original number? • Very big • Big • Large • About same • Small • Tiny • Very tiny

13. 14 of 40 1c requires expressing 2.50 hp in μW. Do you need to know anything about what hp is? • Yes • No • Abstain

14. 12 of 40 Since the required unit uses W, not hp, you need a relationship. You are given 1 hp = 746 W. The given value is then • 746 W • 2.5/746 W or about 0.0035 W • 1.865 W • 1865 W • Other

15. 14 of 40 Does this mean 1865 W is the answer? • Yes • No • Abstain • Afraid to answer

16. 15 of 40 Yes, 1865 W equals the given value. But no, the problem requires an answer in μW. This answer will be about • 2 μW • 2000 μW • 2 000 000 μW • 2 000 000 000 μW • 0.002 μW • 0.000 002 μW • Other

17. Because μW is a tiny unit, the number with it will have to be large. The expected answer is either 1.865 x 109μW or 1.86 x 109μW or 1.87 x 109μW.

18. 13 of 40 1d requires expressing 58 km in cm. The answer is • 58000 cm or more • 580 cm • 5.8 cm • 0.58 cm • 0.058 cm • 0.000 58 cm • Other

19. 14 of 40 1e gives 4.2 ft2 and requires cm2. I know 1 foot is 12 inches, so 4.2 ft2 times 12 in/1 ft will give 50.4 in2. Right? • Right • Wrong • Abstain

20. Wrong. ft2 represents ft x ft, one factor of 12 in/1 ft can only cancel one factor of ft. The number 50.4 would appear with a unit of (ft)(in). Full credit can be earned by converting to inches, PROVIDED you remember and use the correct relationship between inch and cm: cm is smaller (but NOT 1 to 10; inch is not metric). The expected approach is to use the given relation 1 ft = 0.30 m, twice, or squared, and 1 m = 100 cm, also twice or squared. UNITS OBEY RULES OF ALGEBRA.

21. 1f asks for m/s. The numerator unit is • mile • minute • meter • other

22. 15 of 40 1f gives 10.8 km/hr and requires m/s. km is bigger than m and hr is bigger than s. Right? • Right • Wrong • One right, one wrong • Can’t say

23. 15 of 40 Since km is bigger than m and hr is bigger than s, the number in the answer will be • Much larger, the factors reinforce • Much smaller, the factors reinforce • Not extremely different, the factors tend to cancel • Can’t tell

24. km is in the numerator; hr is in the denominator, so factors with the same value would cancel. However, hr is NOT related by metric factors, so the arithmetic is more complicated. 10.8 km/hr x (1000 m/1 km) (1 hr/60 min) (1 min/60 s) = 3 m/s

25. Some cautions: • In PowerPoint I am very limited in writing fractions unless I use a/b format. But in a/b format, especially when there might be fractions inside a or b, it is easy to confuse numerator factors with denominator factors, and to cancel matching numerator factors or matching denominator factors. Remember that for legal canceling, the matching factors must be one multiplying the numerator and one multiplying the denominator. • m is the symbol for meter. It is therefore NOT acceptable for minute, nor for mile, except in certain unmistakable COMBINATIONS (such as MPH or 6h30m).