Biot Savert law with two parallel conductor with complete expalanation

Awoman holds a book by placing it between her hands such that she presses at right angles to the front and back covers. the book has a mass of m = 1.8 kg and the coefficient of static friction between her hand and the book is μs = 0.67. no attempt 50% part (a) what is the weight of the book, fgb in newtons?

Give one example to show that when substances are mixed,it may result in a chemical or a physical change depending on the conditions.

Could we see a galaxy that is 20 billion light-years away?