Suppose that a large controlled experiment tests whether caffeine improves reaction times. a very large number of randomly selected participants are randomly given identical-seeming pills with varying doses of caffeine (including none) and then given tests of reaction times under the same conditions. the experiment finds a strong negative correlation between caffeine dose and reaction time. (note that lower reaction times are better.)1. there is evidence that caffeine causes lower (better) reaction times.2. people with lower (better) reaction times generally choose to consume more caffeine.3. lower reaction times are associated with higher caffeine doses, but this study provides no evidence that caffeine causes lower reaction times.4. there is no relationship between reaction time and caffeine.

Your starship, the aimless wanderer, lands on the mysterious planet mongo. as chief scientist-engineer, you make the following measurements: a 2.50-kg stone thrown upward from the ground at 14.0 m/s returns to the ground in 5.70 s ; the circumference of mongo at the equator is 2.20×10^5 km ; and there is no appreciable atmosphere on mongo. (a) the starship commander, captain confusion, asks for the following information: what is the mass of mongo? (b) if the aimless wanderer goes into a circular orbit 2.20×10^4 km above the surface of mongo, how many hours will it take the ship to complete one orbit? (c) an unmanned spacecraft is in a circular orbit around the moon, observing the lunar surface from an altitude of 44.0 km . to the dismay of scientists on earth, an electrical fault causes an on-board thruster to fire, decreasing the speed of the spacecraft by 23.0 m/s . if nothing is done to correct its orbit, with what speed (in km/h) will the spacecraft crash into the lunar surface?