Question

i. why is friction called a necessary evil ?
ii.what are the changes occur during adulescence
iii. what is cell wall ? give it's role in the cell body.
iv. A girl is 11 years old and 125cm tall. find her height at the end of the growth period using the formula?
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Answer 1

Answer:

Explanation:

why is friction called a necessary evil ?

Frictional force causes a lot of losses in general upkeep and wear and tear of machinery. Hence it is considered as a evil. But almost all crucial tasks cannot be carried out without the presence of friction. ... Hence it is considered as a necessary evil .

what is cell wall ? give it's role in the cell body

A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mechanism.