You manage to organize an event where all the faculty, staff, and students at PCC gather by the mirror pools to jump upwards, as high as they can, in unison, in order to push the Earth downward. Make an order-of-magnitude estimate of the speed they manage to impart to the Earth as a result of the synchronized jump. As always, clearly state the quantities you are estimating.

The focal length of a relaxed human eye is approximately 1.7 cm. when we focus our eyes on a close up object, we can change the refractive power of the eye by about 16 diopters. (a) does the refractive power of our eyes increase or decrease by 16 diopters when we focus closely? explain. (b) calculate the focal length of the eye when we focus closely.

Which best represents the law of conservation of mass ?

Assume that a person skiing high in the mountains at an altitude of h = 15100 ft takes in the same volume of air with each breath as she does while walking at sea level. determine the ratio of the mass of oxygen inhaled for each breath at this high altitude compared to that at sea level. assume that the air composition (i.e. % of air that is oxygen) is the same at sea level as it is at 15100 ft.