Text questions that are similar to the ones below:
CQ 1.2, 1.6, 1.13
P 1.3, 1.6, 1.14, 1.20, 1.33, 1.44, 1.38...
Conceptual Questions:
Most of this lecture is conceptual anyway, so the "numerical" problems below are pretty conceptual. Here are a few additional, more essay-like, questions.
1. Why should one be concerned about "significant figures" in a calculation? (P-1.13)
2. How does a model differ from a theory? (CQ-1.2)
3. How does a model differ from 'reality'? (CQ-1.6)
Numerical Problems:
1. Assume everyone in the United States consumes one soft drink in an aluminum can every two days. If there are 270 million Americans, how many tons of aluminum need to be recycled each year if each can weighs 1/16 pound and one ton = 2000 pounds? Estimate without a calculator. (P-1.3)
ans: 1.5 million tons.
2. Which formula is dimensionally consistent with an expression that would yield a value for 1/time [v is velocity (l / t), x is distance (l), and t is time]?
a. v / x.
b. v2 / x.
c. x / t.
d. v2 / t.
3. Note the expression: y = A/x3. Which statement is most consistent with this expression?
a. y is less than A.
b. If x is halved, y is multiplied by eight.
c. If x is doubled, y is multiplied by eight.
d. y is greater than x.
4. If the displacement of an object, x, is related to velocity, v, according to the relation x = Av, the constant, A, has the dimension of which of the following?
a. Acceleration (l/t2).
b. Length.
c. Time.
d. Area.
5. A cereal box has the dimensions of 0.19 m x 0.28 m x 0.07 m. If there are 3.28 feet per meter, then what is the volume of the box in cubic feet? (P-1.20)
6. A train slowly climbs a 500 m mountain track that is at an angle of 10 degrees with respect to the horizontal. How much altitude does it gain?
7. The distance to the Andromeda Galaxy is estimated at about 2x106 light years. A light year is the distance traveled by light in one year. If the speed of light is 3xl08 m/s, about how far is it from our galaxy to Andromeda? (1 year = 3.15x107 s) (P-1.6)
ans: 1.9x1022 m.
8. Which one of the choices below represents the preferred practice regarding significant figures when multiplying the following: 10.5 x 8.8 x 3.14? (P-1.33)
a. 290
b. 290.136
c. 290.1
d. 300
9. Water flows into a swimming pool at the rate of 8 gal/min. The pool is 16 ft wide, 32 ft long and 8 ft deep. How long does it take to fill? (1 U.S. gallon = 231 cubic inches)
ans: 64 hours.
10. Which point is nearest the origin (hint: sketch it out)?
a. (-3, 4 ).
b. ( 4, 5 ).
c. (-5, 3 ).
d. ( 5,-2 ).
’
11. Modern electroplaters can cover a surface area of 60 m2 with one troy ounce of gold (volume = 1.611 cm3).What is the thickness of the electroplated gold? (P-1.44)
ans: 2.68x10-8 m.
12. A high fountain of water is in the center of a circular pool of water. You walk the circumference of the pool and measure it to be 150 meters. You then stand at the edge of the pool and use a protractor to gauge the angle of elevation of the top of the fountain. It is 55 degrees. How high is the fountain? (P-1.38, well maybe,,,)
13. The mass of the sun is 2x1030 kg, and the mass of a hydrogen atom, of which the sun is mostly composed, is 1.67x10-27 kg. How many atoms are there in the sun (don't use a calculator for this one)? (P-1.14)
ans: 1.2x1057 atoms.