1. What problems could arise if people used different units to measure
the same thing?
2. If you measure a table as 2 meters long using a tape measure, but
your friend measures it as 205 cm, who is correct? Explain.
3. A carpenter needs to cut a piece of wood that is exactly 1.5 meters
long. If their measuring tape is only marked in centimeters, what
number should they look for?
4. What tool would you use to measure the length of your pencil? Why?
Answer (1)
1. There are many stories of problems occurring with different units. My favorite is when the US and Europe collaborated to build a deep space probe. After the launch, the probe sailed off into space. Before it could get any data, it went off-course. The problem was that the design of a navigation control system was done in Europe and the design was sent to the US for manufacture. The US assuming everything was in inches. The design was in cm. $300 million unit error.2. 2 meters equals 200 cm, so we can't say there is a unit problem. We aren't told what the friend was using as a measuring device. If we assume both use a tape measure, with the same resolution, then your measurement of 205 cm is likely the correct answer. 205 has 3 significant digits, while 2 only has 1. If someone reports 205 cm, then it is inferred that the measurement was accurate to the nearest cm.3) 1.5 meters is equal to 150 cm.4) A ruler maked to the nearest 1/8 inch or 1 mm, since the pencil is short.
