Mensura et figurae significantes – problemata et solutiones
1. Longitudo obiecti mensurata utens micrometer est 15.08 mmDetermina significans figuras et numerus figurarum significativarum.
A. 15.08 mm et tres significans figuras
B. 1.508 mm et quattuor significans figuras
C. 15.08 mm et quattuor significans figuras
D. 1.508 mm et tres significans figuras
solution:
Significant figures = 15.08 mm
The number of significant figures = 4
Responsum rectum est C.
2. A student measures the volume of a container using a small cup with a volume of 125 cm3. The container is full after filled with twenty-half cups. Determine the volume of container based on significant figure rules.
A. 2562.5 cm3
B. 2.56 × 103 cm3
Circa decem centimetra3
D. 2.56 × 10-3 m3
solution:
Volume of a cup = 125 cm3
Volume of container = 20.5 x 125 cm3 = X cm3
Responsum rectum est A.
3. Determina the result of measuring an object as shown in figure below, according to the rules of significant figures.
A. 4.5 mm
B. 4.6 mm
Circiter 4.6 mm
Diametrum 4.6 mm
solution:
Scala principalis = 4.5 mm
Second scale = 11 x 0.01 mm = 0.1 mm (according to the rules of the multiplication of significant figures)
The result of measuring = 4.5 mm + 0.1 mm = 4.6 mm (according to the rules of the summing of significant figures)
Responsum rectum est C.
1. PROBLEMATIS Round 27.6891 to four significant figures.
Solutio: 27.69 (because 1 doesn’t affect the third decimal place).
2. PROBLEMATIS If you multiply 6.34 (3 significant figures) by 5.678 (4 significant figures), how many significant figures should your answer have?
Solutio: The answer should have 3 significant figures.
3. PROBLEMATIS A scientist recorded a result of 5001 grams. How many significant figures does this value have?
Solutio: 4 significant figures.
4. PROBLEMATIS What is the result when you add 24.5 (3 significant figures) and 1.789 (4 significant figures)?
Solutio: The sum is 26.289, but considering significant figures, you should round to 26.3.
5. PROBLEMATIS If a physics experiment gives a speed of 0.0056078 m/s, how many significant figures are there?
Solutio: 5 significant figures.
6. PROBLEMATIS Round 0.007809 to four significant figures.
Solutio: 0.007809 (because it already has four significant figures).
7. PROBLEMATIS When measuring the depth of a well, you get a value of 78.00 meters. Later, another reading says 78.0001 meters. If you average the values, how many significant figures should your answer have?
Solutio: The average should have 4 significant figures. Thus, 78.00 + = 78.00012 78.00005 becomes 78.00.
8. PROBLEMATIS You measure the width of a book as 150 mm. How many significant figures are there?
Solutio: 2 significant figures.
9. PROBLEMATIS What is the result when you divide 90.12 (4 significant figures) by 4.0 (2 significant figures)?
Solutio: The result is 22.53, but considering significant figures, the answer should be rounded to 23.
10. PROBLEMATIS You measure 0.4000 liters of liquid A and 0.4020 liters of liquid B. When reporting the total volume, to how many decimal places should you report your answer?
Solutio: You should round to 4 decimal places. Thus, 0.4000 + = 0.4020 0.8020.
11. PROBLEMATIS Round 50.0012 to five significant figures.
Solutio: 50.001 (because 2 doesn’t affect the fourth decimal place).
12. PROBLEMATIS When subtracting 45.67 (4 significant figures) from 100.1 (4 significant figures), how many significant figures should your answer have?
Solutio: The answer should have 4 significant figures. So, 100.1 – 45.67 = 54.43.
13. PROBLEMATIS A result was documented as 1020 with no decimal point. How many significant figures does this have?
Solutio: 3 significant figures.
14. PROBLEMATIS What’s the result when you subtract 2.3456 (5 significant figures) from 5.00 (3 significant figures)?
Solutio: The result is 2.6544, but considering significant figures, you should round to 2.65.
15. PROBLEMATIS How many significant figures are in the number 0.005002?
Solutio: 4 significant figures.
16. PROBLEMATIS Round 10.4987 to three significant figures.
Solutio: 10.5.
17. PROBLEMATIS You get a voltage reading of 50.00 V from one instrument and 50.0005 V from another. If you average the readings, how many significant figures should the result have?
Solutio: The average should have 4 significant figures. So, 50.00 + = 50.00052 50.00025 becomes 50.00.
18. PROBLEMATIS The length of a rod is measured to be 200 mm. How many significant figures does this measurement have?
Solutio: 1 significant figure.
19. PROBLEMATIS You’re dividing 4.56 (3 significant figures) by 2.0 (2 significant figures). What should be the number of significant figures in the answer?
Solutio: The answer should have 2 significant figures. So, 4.56 ÷ 2.0 = 2.28.
20. PROBLEMATIS The measured distance between two towns is 100.50 km. How many significant figures does this measurement have?
Solutio: 5 significant figures.
