The mass of a uniform metal rod is directly proportional to its length. A 2.5 metre rod has a mass of 7 kilograms. What is the mass of a 6 metre rod? Enter the number of kilograms.

Объяснение

The mass per metre is 7 divided by 2.5, which is 2.8 kilograms, so 6 metres has a mass of 16.8 kilograms. Simply adding the 3.5 metre length increase to 7 would mix metres with kilograms and would not apply the constant scale factor.