Which of these IS an example of balanced forces?

A. a book on a shelf
B. air rushing out of a balloon
C. rolling over and falling off the bed
D. a car speeding up at a constant rate

How can you measure the amplitude of a longitudinal wave?

The safe load, l, of a wooden beam of width w, height h, and length l, supported at both ends, varies directly as the product of the width and the square of the height, and inversely as the length. a wooden beam 4 inches wide, 9 inches high, and 240 inches long can hold a load of 6810 pounds. what load would a beam 3 inches wide, 8 inches high, and 144 inches long, of the same material, support? (round off your answer to the nearest integer.)

5400 j of energy are given off when a 50 g of aluminum pan changes temperature. does the temperature of the pan increase or decrease and by how much