91. Which of the following represents a decimal system of measurement?
Metric system represents a decimal system of measurement. This means that different units differ from one another by some multiple of "10".
Answer: 1 kilometer = 1,000 meters
113. You measure the mass of a 0.500 kg (500 g) standard on your balance four times. The following measurements result: 498 g, 501 g, 499 g, 500 g. Which of the following best describes your balance?
Since you measured the mass of a 500 g standard on your balance, to be accurate, the results should be close to the standard mass of 500 g. Since the data varies only by 2 grams at the most, and its average is 499.5 g, your balance is accurate and precise. Accuracy refers to its closeness to the standard mass value, and precision refers to how close the measurements are to each other.
Answer: precise and accurate
114.If a box has a length of 10.0 cm, a width of 20.0 cm, and a height of 5.00 cm, then what is its volume in m^3?
Since the answer must be in cubic meters, then we can first convert each measurement to meters by dividing it by "100" or moving the decimal point two places to the left:
10.0 cm = 0.100 m
20.0 cm = 0.200 m
5.00 cm = 0.0500 m
Next, let's multiply the three measurements to get the volume in cubic meters:
(0.100 m)(0.200 m)(0.0500 m) = 0.00100 m^3 or 1.00 × 10^-3 m^3 rounded to three significant figures
Answer: 1.00 × 10^-3 m^3
115. What is the difference between 3.15 m and 2.0 m with the correct number of significant figures?
To do this, subtract 2.0 m from 3.15 m and round to one place to the right of the decimal point:
(3.15 m) – (2.0 m) = 1.15 m or 1.2 m
Answer: 1.2 m
116. Which of the following measurements has two significant digits?
0.05 kg = has only one significant figure "5", because leading zeroes are never significant even when there is an expressed decimal point in the number
50 m = has only one significant figure "5", because trailing zeroes are only significant when there is an expressed decimal point in the number
0.2 s = has only one significant figure "2", because leading zeroes are never significant
0.030 g = has two significant figures "3" and "0" to the right of "3", because while the leading zeroes are never significant, the trailing zeroes are significant when there is a decimal point expressed somewhere within the number
Answer: 0.030 g