Experiment 1 Rulers vs Calipers In this experiment you will compare the precision and accuracy measuring the same objects with a ruler and a caliper Materials 1 Marble Ruler String 1 8 oz Styrofoam Cup Vernier Caliper 1 Washer Procedure Using the ruler measure the diameter of the marble Record your measurement in Table 1 1 Indicate your uncertainty Record the uncertainty in Table 1 2 Repeat Steps 1 and 2 for the outer diameter of the washer inner diameter of the washer washer thickness length of the string and the height of the Styrofoam cup 3 Repeat Steps 1 3 using a Vernier caliper Table 1 Ruler and Caliper Measurements Ruler Object Marble Diameter Measurement cm Uncertainty cm Caliper Measurement cm Uncertainty cm 1 0cm 0 05cm 1 20cm 0 0025cm Washer Outer Diameter 1 8cm 0 05cm 1 80cm 0 0025cm Washer Inner Diameter 0 8cm 0 05cm 0 80cm 0 0025cm Washer Thickness 0 1cm 0 05cm 0 13cm 0 0025cm String Length 5 9cm 0 05cm 5 94cm 0 0025cm Styrofoam Cup Height 9 1cm 0 05cm 9 02cm 0 0025cm Post Lab Questions 2014 eScience Labs LLC All Rights Reserved 1 Compare the measurements for objects using the ruler and caliper and write a general statement on when it is more beneficial to use a ruler rather than a caliper Measurements on a ruler are less exact than that on a caliper Additionally a ruler would be a more useful when you are measuring a 2D object because the caliper does not lay smoothly against a surface 2 Comment on accuracy vs precision for rulers and calipers The caliper always give a more precise and accurate reading and you can use one more decimal place because of how exact the measurements are laid out Accuracy is how close the measurement is to the true value and because you can measure to a smaller measurement the readings are more exact The ruler is less exact and so is unable to provide the amount of exactness that a caliper can 3 What are the sources of uncertainty when using a ruler and caliper The smallest graduations on a ruler is 0 1 cm and so taking the half least count in an uncertainty you get 0 05cm The smallest graduations on a caliper is 05mm so using the half least count for this item you have an uncertainty of 0 025mm or 0 0025cm 2014 eScience Labs LLC All Rights Reserved Experiment 2 The Spring Force Scale Before you begin an experiment using the spring scale you may need to calibrate it In this experiment you will become familiar with how to calibrate and use the spring scale Materials Mass Set Roll of Masking Tape Box of Modeling Clay Single Hole Punch 5 N Spring Scale 10 N Spring Scale Stopwatch Procedure Calibrating a Spring Scale 1 Hold the 5 N spring scale by the handle so that the measurement readings are right side up This should leave the hook hanging from the bottom 2 Observe the plunger the plastic piece hanging from the spring as you gently pull and release the hook The top of the plunger that looks like a flat circular piece is called the indicator 3 To calibrate the spring scale observe the position of the indicator on the measurement scale The indicator should rest at 0 g or 0 N when no force is applied i e the hook is not being pulled on by anything 4 If the indicator is in any position other than zero when at rest adjust it by twisting the plastic bolt at the top of the spring scale until the indicator rests at the measurement 0 g or 0 N 5 Repeat Steps 1 4 with the 10 N spring scale Weighing a Mass 1 Calibrate the 5 N spring scales if necessary 2 Hold the spring scale upright by the metal handle and hook the stopwatch onto the spring scale hook so it freely hangs 3 Observe how far the indicator moves on the measurement scale and record the mass in Table 2 4 Determine and record the uncertainty in Table 2 5 Repeat Steps 1 5 using the 10 N spring scale 2014 eScience Labs LLC All Rights Reserved 6 Repeat Steps 1 6 for the box of modeling clay roll of masking tape and single hole punch Table 2 Spring Scale Measurements Object Stopwatch 5 N Spring Scale Weight g 40g Uncertainty g 10 N Spring Scale Weight g Uncertainty g 10g 2 5g 40g 20g 2 10g Modeling clay 470g 10g 2 5g 460g 20g 2 10g Masking tape 70g 10g 2 5g 80g 20g 2 10g Hole punch 45g 10g 2 5g 50g 20g 2 10g Post Lab Questions 1 What are the advantages and disadvantages of using a spring scale to measure weight A disadvantage is that for this particular scale you have to have a way of hanging the object without it singing about This could be fixed by creating some sort of basket to hold items and then canceling out that weight An advantage is that it provides a quick and easy way to measure items 2 What are sources of uncertainty when using a spring scale The uncertainty was 5g for the 5N scale and 10g for the 10N scale You also have to be careful to ensure that the spring is not bouncing up and down once an object has been hung to be weighed You must ensure that the object is suspended in the air at a stationary position 2014 eScience Labs LLC All Rights Reserved Experiment 3 The Stopwatch In this experiment you will investigate error and uncertainty involved with using a stopwatch Materials 1 Marble Stopwatch Constant Drop Height Ex Table Top or Door Frame You Must Provide Procedure 1 Choose a place or object like a table top or top of a door from which you can constantly drop a marble at the same height Note Choosing an object that has a higher drop distance will be easier to time than shorter drop distances 2 Read the directions that come with your stopwatch to become familiar with how to use and access the stopwatch mode 3 Hold the marble at the designated drop height in one hand and the stopwatch in the other hand If necessary a willing participant can help with timing or dropping the marble 4 Drop the marble from the designated drop height and start the stopwatch at the same time 5 Stop the stopwatch at the same time the marble hits the floor Record the time in Table 3 6 Repeat Steps 3 4 four more times for a total of five trials Table 3 Time Data for Dropped Marble Drop Trial 1 Time s 63 seconds 2014 eScience Labs LLC All Rights Reserved 2 61 seconds 3 60 seconds 4 68 seconds 5 59 seconds Post Lab Questions 1 What are the advantages and disadvantages of using a stopwatch to measure time A disadvantage to timing with a stopwatch is the room for human error There is no way to completely take human error because the person …
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