Gizmo is an online learning platform that allows the students for learning science and math. Gizmo Unit Conversions 2 is one of the subjects that you will learn on Gizmo. If you want to take Unit Conversions 2 test on Gizmo, you may want to know the answer to pass the test. Here you are going to get the answer key for Gizmo Unit Conversions 2
Gizmo Answer Key – Gizmo Unit Conversions 2
Activity A: Scientific Notation
Question: How can you convert numbers into and out of scientific notation?
- Observe: Some of the problems in this Gizmo involve very small or very large quantities. Look at the bottom three Unit Conversation Tiles. What do you notice in the numerator?
Answer: Written in scientific notation
- Convert: To convert a number written in scientific notation into a standard number, first look at the exponent on the base. If it is positives, move the decimal point on the coefficient to the right as many times as the exponent indicates, as shown below:
| Look at exponent | Count digits | Move decimal point | Standard form |
| 8.35 x 10 | 8.3 500 000 | 83 500 000.0 | 83,500,000 |
Practice converting the two numbers below into standard form:
1.0 .109 = 100,000,000
6.72 .1012 = 672,000,000,000
- Solve: Look at the last tile!
A: How many kilometers are equal to 1 light year?
Answer: 9.461x
B. Write this number in standard form:
Answer: 9,461,000,000,000
C. Drag this tile below to solve the problem. Turn on Show result. What is the distance to Proxima Centauri in kilometers?
Answer: 4.013x
D. Write this distance in standard form:
Answer: 4,013,000,000,000
- Convert: Not all numbers written in scientific notation are very large numbers. Scientific notation also can be used to write very small numbers. This is done by making the exponent on the base negative, indicating the decimal point should be moved to the left.
| Look at exponent | Count digits | Move decimal point | Standard form |
| 7.9 x 106 | 000 007.9 | 0.000 007.9 | 0.0000079 |
Try converting these numbers into standard form:
1.0 . 10-10 = .0000000010
1.6 . 10-7 = .00000016
- Practice. Click Next so that you see the question about a helium atom.
A. What is the diameter of a helium atom in meters?
B. Write this number in standard form:
Answer: 0.000000000098
Activity B: Significant Digits
Question: What digits are significant, and why?
- Think about it: Mark measures the volume of water in a beaker marked in 50-mL intervals. He reports the volume is 43.927 mL. What is misleading about this value?
Answer: The measurements may be wrong as they are not rounded.
- Practice: Look at the quantities mentioned in the Metric units only distance problems. For each value, state the number of significant digits in the first column and the rules you used to determine the number of significant digits. The first has been done for you.
| Question | Number of Significant digits | Rule(s) used |
| The tallest building in the world, the Burj Khalifa in Dubai, is 0.828 kilometers high | 3 | 1,4 |
| The largest human cell is the gg cell, with a diameter of 121 micrometers | 3 | 1 |
| On a caterpillar’s map, all distances are marked in millimeters. The caterpillar’s map shows that the distance between two milkweed plants is 4,012 milimeters | 4 | 1,2 |
| The closest star to our Sun is Proxima Centauri, which is 4.242 light years away | 4 | 1 |
| A helium atom has a diameter of 9.8 . 10-11 meters. | 2 | 5 |
- Practice: The following quantities are all found in the Speed problems. State the number of significant digits in the first column and the rules you used to determine the number of significant digits.
| Metric units only | Mixed units | ||||
| Value | Significant digits | Rule (s) | Value | Significant digits | Rules |
| 3.50 m/s | 3 | 1,3 | 113 km/hr | 3 | 1 |
| 72 km/hr | 2 | 1 | 1,25 mi | 3 | 1 |
| 4.25 min | 3 | 1 | 2.00 min | 3 | 1,3 |
| 2.0 . 103 um/s | 2 | 1,5 | 9.58 s | 3 | 1 |
| 45.215 d | 5 | 1 | 1.0 yd/d | 2 | 1,3 |
| 60,004,000 km | at least 5 | 1,6 | 1.02 mm/hr | 3 | 1,2 |
Activity C: Calculating with Significant Digits
Question: If you multiply or divide two numbers, how many significant digits are in the answer?
- Observe: The first metric speed question is about Marcia, who ran at a speed of 3.5 meters per second. How many significant digits are in this value?
Answer: 3
- Solve: Use the tiles to convert Marcia’s speed to kilometers per hour. When you are finished, turn on Show result and click Submit to check if the answer is correct.
A. What value do you get?
Answer: 12.6 km/h
B. How many significant digits are in this value?
Answer: 3
- Learn a rule: In any calculation, the number of significant digits in the answer should not be greater than the number of significant digits of any measured value. For example, suppose you do the following area calculation: 5.73 cm • 2.1 cm = 12.033 cm2
- Practice: Turn off Show results and click Next. For each of the remaining metric speed problems, predict the number of significant digits in the answer. Then, solve each problem and write the answer value and number of significant digits. Turn on Show results to check your answers.
A. A Tuna travels at a speed of 72 kilometers per hour. What is the speed of the tune in meters per second?
Answer: Predicted number of significant digits in answer: 2, Answer value: 20 m/s, Actual number of significant digits: 2
B. A Slug takes 4,25 minutes to travel 11,2 centimeters. What is the speed of the slug in meters per second?
Answer: Predicted number of significant digits in answer: 3, Answer value: 4,39 x, Actual number of significant digits: 3
C. A paramecium is a single celled organism that lives in ponds. It travels at a rate of 2,000 micrometers per second. What is the speed of the paramecium in meters per hour?
Answer: Predicted number of significant digits in answer: 2, Answer value: 7,2, Actual number of significant digits: 2
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