Draw the free body diagram for a 12n book sitting on a table

draw all the forces acting on the book

NB free body is represented using a Dot

it doesn't. it was imagined up in the middle ages.

the skeletons of most mammals reach a certain size and then stop growing. however, many animals, including some mammals, keep growing throughout their lives. kangaroos, for example, just keep growing and growing until they die. also, the longer an animal lives the greater the chance it might catch some deadly disease.