1 to 8 17. Turn off the balance. Questions . Why is it necessary to quantify you

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17. Turn off the balance. Questions . Why is it necessary to quantify your 2. Why should there be accepted quantities 18. What is the maximum mass that can be recorded using this balance? How many significant figures would this measurement have? What purpose do the edges of the weighing boat serve? observations? (standards) that are measured? List the quantities covered in this exercise. 3. What should you do if the specimen or Procedure 2.5 object that you are measuring the length of is much smaller than the standard for length? For mass? Measuring Temperature 4. What are the units that represent the least Although the base quantity for temperature in the SI is measured in kelvins (K), biologists usually measure temperature in degrees centigrade (°C). count on the scale of the meter stick? Graduated cylinder? Balance? and Thermometer? 273.15 K 0°C 5. Make four of your own practice measurements using four different scales provided in Figure 2.1 on page 17. Include a unit for each measurement. I. Obtain a 100 °C centigrade thermometer from the rack on the counter. Make sure that the alcohol (red) column visible in the barrel is visible and is not broken. 6. If an object has a length of 5.65 cm and a width of 3.15 cm, the raw area is calculated to be 17.7975 cm2. Are all of these digits Obtain a 400 ml beaker from the cabinet and add 250 ml of cool or lukewarm tap water to the beaker 2. significant? Why or why not? If not, what is the accepted area of this object? How does estimation in a measurement maintain uncertainty in science? 3. Carefully place the thermometer into the beaker and wait five minutes. 8. State the difference between accuracy and 4. Measure the temperature of the water in degrees centigrade (°C) and record this value in your lab notebook. Remember to record precision Exercise 2: Scientific Measurement

Explanation / Answer

1. This is to make your data more objective so that it is easier to understand and analyse it with out making wild assumptions.This also helps one to represent it in a way that can be better understood by others.

2. Standards of measurements are required to have a uniformity in the measurement of any parameter through out the scientific world. If we have same standards, a parameter measured in one place can be compared with another of its measurement done at a different place or time. Kelvin the unit of temperature is a unit of time, milli litre is an accepted quantity of measurement of volume

3. In this case we can shift to smaller standards of measurement of lenght and mass. like if you are measuring the diameter of a microbial cell meter cannot be used as a unit of this length, since microbial cells are of micrometric in diameter. so here shift the unit to micrometer, a smaller unit of lenght measurement, than meter.

6. According to rule of significant figures all non zero digits are significant. There are 3 significant figures in length measurement and 3 significant figures in breadth measurement. The significant figures in the product should not be more than the least number of significant figures in the the multiplied numbers. So here both the multiplied numbers have 3 significant figures, so the area measurement will have only 3 significant figures, so the value will be 17.7 . SInce the next digit is more than 5 that is 9, we can round off the value to 17.8

4. In a meter stick milli meter is the lowest count., on double pan balance it is 0.1g, in smallest graduated cylinder it is 25ml,and in thermometer it is 10C.

8. Accuracy gives an idea of how close one is to the correct result.

Precision is how often your measurements are reproducible, or how consistent are you results.

One a be precise and be inaccurate, means a person can reproduce the same false results consistently

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