thsom wrote:Hey guys, I have two questions. First, How do you continue your powders tests when you don't have any phenolphthalein to test with or alcohol for solubility? I ran into those problems in a test. Second, when referring to the angle of the blood splattering, how do you calculate that and which angle is it referring to (the angle between the opposite side and the hypotenuse or the angle between the adjacent side and the hypotenuse if you are using a right triangle to solve for it)?

First, why are phenolphthalein and alcohol absolutely necessary? The reagents provided will work as long as you know what identifies what. It helps to have a flowchart for the powders as well, making sure that all the steps are actually feasible using what's given and not very time-consuming at competition.

As for angle of impact on blood spattering, it is

, where theta is the angle, W is the width, and L is the length. arcsin is also known as reverse sine. No complex computations required. Well, of course, arcsin is related to trig, but calculating trig by hand is not required. Seriously, don't try to make it hard on yourself.