Abook is sitting on a desk. what best describes the normal force acting on the book? a)the upward force the desk pushes on the book b)the upward force the book pulls on the earth c)the downward force the book pushes on the desk d)the downward force the earth pulls on the book

A) the upward force the desk pushes on the book.

from the free body diagram of the book, it is clear that on the book, there are two forces acting.

1) normal force F by the desk in Upward direction.

2) force of gravity by earth in downward direction.

The Upward normal force by the desk on the book balances the force of gravity by earth in downward direction. that is why the book remains stationary on the desk.

total distance travelled = 60 miles

total time taken =1.5 hours

average speed = total distance / total time

60 / 1.5

= 40

therefore, average speed = 40 m/h

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vapour or gas assuming atmospheriv pressure