Question

Which scale is best for measuring the length of a ladybug?
(A) millimetres
(B) centimetres
(C) metres
(D) kilometre

Answer 1

To measure any object's length, it is measured with the help of the metric systems. The most common units which are used widely in physics to measure the length of the object in the metric system are millimetres, centimetres, metres and kilometres.

Complete step by step solution
Millimetre:
The millimetre is the unit which is commonly used to measure the smallest object. The units which are available to measure the smallest object than the millimetre. The millimetre is the smallest unit to measure the object which is visible to the human eye clearly. Some other objects are visible to the human eye but not clear, that type of objects is measured by other terms available. The abbreviation of the millimetre is $mm$ and the milli denotes that ${10^{ - 3}}$.

Centimetre:
The centimetre is the next smallest unit of measurement, which measures the objects which are little larger than the millimetre objects. There are $10$ millimetres in the $1$ centimetres. And the abbreviation of the centimetres is $cm$ and the centi denotes that the ${10^{ - 2}}$.

Metre:
The next common metric unit is metre. The abbreviation of the metre is $m$. The easy way to understand the metre length is that, stretching your two hands horizontally, from the fingertip of the right hand to the fingertip of the left hand shows approximately one metre.

Kilometre:
The kilometre is the measuring unit which measures the longest distance. There are a thousand metres present in the one kilometre. The abbreviation of the kilometre is $km$.

Thus, the lady bug is the smallest insect and it is visible to the eye, so that the best scale for measuring the length of the lady bug is centimetre.

Hence, the option (B) is the correct answer.

Note: One kilometre is equal to the thousand metres. And then one centimetre is equal to the $0.01$ metre, and one millimetre is equal to the $0.001$ metre. For example, if the length of the object is $10$ millimetre, this length value is also represented as $1$ centimetre.