Precise measurements of physical quantities are a need of science. For example, to ascertain the speed of an aircraft, one must have an accurate method to find its positions at closely separated instants of time. This was the actual motivation behind the discovery of radar in World War II. Think of different examples in modern science where precise measurements of length, time, mass etc. are needed. Also, wherever you can, give a quantitative idea of the precision needed.

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Solution

Precise instruments are used to take precise and accurate measurements. In certain kinds of activities, the measurement needed must be precise.

For example, in a nuclear reaction, the time of collision of the neutron with the radioactive neutron is extremely precise. In radiography technique, the separation between the inter-atomic distances is measured by a precise instrument. In case of several chemical processes, the time interval is calculated with the help of ultra shot laser pulses.

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Similar questions

Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity):

(a) The total mass of rain-bearing clouds over India during the Monsoon.

(b) The mass of an elephant

(d) The number of strands of hair on your head

(e) The number of air molecules in your classroom

Is it necessary that a measurement which is accurate must be precise or a measurement which is precise must be accurate?

Many discoveries in science have been accidental. This is true for plant hormones also. Can you justify this statement by giving an example? Also what term is used for such accidental findings?

Q. Assertion :In the measurement of physical quantities direct and indirect methods are used. Reason: The accuracy and precision of measuring instruments along with errors in measurements should be taken into account, while expressing the result.

Difference between precise and accurate measurement.

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