21. When air is blown into a balloon, it expands equally in all directions. The best explanation for this is (circle the correct answer): A - The gas molecules in the balloon are expanding B - Internal air pressure acts at right angles to the balloon surface. C - As more air is blown in, the temperature increases causing the balloon to expand.

Asilver dollar is dropped from the top of a building that is 1324 feet tall. use the position function below for free-falling objects. s(t) = −16t2 + v0t + s0 (a) determine the position and velocity functions for the coin. s(t) = v(t) = (b) determine the average velocity on the interval [1, 2]. ft/s (c) find the instantaneous velocities when t = 1 second and t = 2 seconds. v(1) = ft/s v(2) = ft/s (d) find the time required for the coin to reach the ground level. (round your answer to three decimal places.) t = s (e) find the velocity of the coin at impact. (round your answer to three decimal places.) ft/s

State the below theories and give the name of the writer of the theory 1. wave theory 2. quantum theory 3. corpuscular theory 4. electromagnetic theory

Which is an advantage of subdividing science into different areas?