Tim is experimenting with salts dissolving in water. he thinks that all salts will become more soluble as the temperature increases. he plots the data on the graph and decides that temperature has very little effect on the solubility of a) sodium nitrate. b) sodium chloride. c) potassium iodide. d) potassium nitrate.

i think the answer is a, hope this : )

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me

there are no contact forces mentioned on the list of choices that you've provided.