Suppose that a substance in a beaker is heated over a burner in a science lab. which observation would most likely indicate that a chemical change has occurred in the substance

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

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?

Which of these activities increases the amount of carbon in the atmosphere?