Measurement of Length, Time and Mass Name: Joel Job Mathew Instructor: Dr. Maria Hoss Date: 2 September 2023 Equipment: Stopwatches; String; Ruler; Meterstick; Ball; Round Objects; Triple Beam Balance Objectives: To make basic measurements of length, mass and time. To practice graphing using spreadsheet software and paper and pencil. Estimate Length: 1. Estimate the length of a meter by putting a pen or pencil at one end of a table and placing a second pen or pencil about one meter away from the first. 2. Use the meterstick to measure the actual length of your meter estimate. 3. Record the length of your meter estimate. 4. Calculate the percent error of your estimated meter from an actual meter. %error= (IA-EI/ A)x100. Notice the absolute value in the difference. "A" is accepted (kown) value and "E" is the estimated (experimental value) Estimate Time: 1. Estimate a 30-s time period while someone else times you using a stopwatch. (If you do not have a partner, you can do this experiment by closing your eyes; start the stopwatch and stop it when you think 30 s have elapsed.) 2. Record the actual time of your estimate. 3. Calculate the percent error of the estimate from the actual time. Estimate Mass: You cans kip this part if you don't have at home a spring scale for measuring mass. 1. Pick up a small paperback book or similar small object and estimate its mass. 2. Determine the actual mass of the object using the triple beam balance. 3. Record the estimated mass and the actual mass and calculate the percent error. Data Table 1: Estimation of various measurements Measurement 1.Length (m) 2.Time(s) Estimated Actual % Error Measurement 3. Mass (kg) Estimated Actual % Error In this exercise you will use your hand, a ruler or a tape measure to measure lengths of objects. You will then compare the precision of these different methods. Hand width (Measurement of your hand span) Data Table 2: Measurement of width and height of a door cm m For the second row, measure the door using your hand and then multiply the hand units with the hand width Instrument used Width (cm) Width (m) Height (cm) Height (m) 1.Ruler 2. Hand In this exercise you will use a stop watch (phone) and different cues to measure time. 1. Measure and mark a vertical distance of 2 m from the floor up. 2. Stand on a chair and hold a ball (marble) at the marked height in one hand and the stopwatch in the other hand. 3. Start your stopwatch at the same instant you release the object and stop the timer when you see the object hit the floor. Repeat three times and calculate the average. Data Table 3: Time measurements using visual cues Trial 1: Trial 2: Trial 3: Average: Drop time(s) Repeat by having a family member or a friend time you while you drop the ball - use verbal commands like "start" or "now" to synchronize the dropping and timing. Repeat 3 times, find the average drop time of the object. Data Table 4: Time measurements using auditory cues Trial 1: Trial 2: Trial 3: Average: Drop time (s) In Data table 5 include your measurements of round shaped objects around the lab using string, ruler or meter. You must measure both the circumference and the diameter, do not use the C = D equation. If your graph's slope is the "perfect" t value, you did not complete correctly the exercise. The table and the graph must have D=0 and C=0 values included. Object Diameter D(m) Circumference C(m) 1.keep this row 0 0 2. 3. 4. 5. 6. Graphing data and the determination of based on the values from Data Table 5 The relationship between the circumference and the diameter of a circle is: C = + D 1. Plot C vs D, C- circumference on the Y axis and D- diameter on X axis using EXCEL or paper and pencil then insert the graph below. The graph should be a line; use the "trendline", do not simply connect the points) Calculate the slope of the graph Questions: 1. What are the SI units for length, time, and mass? 2. Can you think of an occasion when it would be adequate to use your "hand" measurement? 3. Calculate the exact time it takes a ball to fall from 2m to the ground using the following equation: h = gt/2, where h=2m and g=9.8m/s. Which of the time measurements (tables 3 and 4) is more accurate? 3. How much is the slope of the graph generated from data table 5? The slope value is the "experimental" value of . 4. Calculate the percentage error between the "experimental" value (the slope of the graph) and the known "accepted" value of =3.1415, using the following formula: %error= (IA-EI/A)x100. Notice the "absolute value" in the difference.