Measurement of Length, Time and Mass
Group Members:
Course Number:
Section Number:
Instructor:
Date:
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.
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:
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)
Estimated
Actual
% Error
2.Time (s)
3. Mass (kg)
1
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) ________ cm_______ m
Data Table 2: Measurement of width and height of a door
Instrument used
1.Ruler
2. Hand *
Width (cm)
Width (m)
Height (cm)
Height (m)
* hand units x hand width
In this exercise you will use a stop watch 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
Drop time (s)
Trial 1:
Trial 2:
Trial 3:
Average:
Let one of the team members 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
Drop time (s)
Trial 1:
Trial 2:
Trial 3:
Average:
2
In Data table 5 include your measurements of round shaped objects around the lab using string,
ruler or meter.
Object
Diameter 𝐷(𝑚)
Circumference 𝐶(𝑚)
1.
2.
3.
4.
5.
6.
Graphing data and the determination of π based on the values from Data Table 5
The relationship between the circumference and the diameter of a circle is: 𝐶 = 𝜋 ∗ 𝐷
1. Plot C vs D, C- circumference on the Y axis and D- diameter on X axis
 Graph C vs. d using a computer spreadsheet program then insert the graph below.
 Draw the graph on a separate piece of paper (the graph should be a line; use “best fit
line” do not simply connect the points)
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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 /2. Which of the time measurements (tables 5 and 6) is more accurate?
3. How much is the slope of the graph generated from data table 7?
4. Calculate the percentage error for the mathematical value calculated using π=3.1415 for the
accepted value.
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