Science
D. Long Answer Questions
1 why is a cubit or a footstep not used as a standard unit of length?
2. What precautions will you take to measure the length of the table top accurately?
3. What do you understand by the term "parallax error'? How can this be rectified?Explain with an
example
Answers
1.
In earlier times, human beings used units like Cubit or a footstep, as units of measurement. However, these length measurement methods are unreliable. It was soon realized that these measurements Could be different For different people. Therefore, units like a handful, cubit, or a foot span were not used as standard units of measurements.
2.
The scale should be placed along the length to be measured.
Your eye must be in front of and in line where the measurement is to be taken.
3.
A parallax error is the perceived shift in an object's position as it is viewed from different angles. The error is most easily noticed by looking at a nearby object with one eye closed, then looking at it through the other eye. The apparent motion of the object is the parallax shift, and it is responsible for a small, but noticeable, error common to optical equipment.
Hope it helps :D