Which phrase describes density?
height of a point above sea level
force pushing on an area or a surface
amount of mass in a certain volume
amount of matter an object contains

Two friends are having a conversation. anna says a satellite in orbit is in freefall because the satellite keeps falling toward earth. tom says a satellite in orbit is not in freefall because the acceleration due to gravity is not 9.80 m/2 . who do you agree with and why?

Animals respond in various ways to stimuli detected through their senses. some of these responses are stimulated by the presence of danger. which of these animal responses is the best example of a response to an immediate threat? a) a rooster crows every morning at the first sign of light. b) as something approaches an octopus, it shoots a cloud of ink. c) from late fall until spring, bears hibernate to preserve energy. reactivate d) a dog is getting hot in the sunlight, so he moves to a shaded area.

The membrane surrounding a living cell consists of an inner and an outer wall that are separated by a small space. assume that the membrane acts like a parallel plate capacitor in which the effective charge density on the inner and outer walls has a magnitude of 7.0 × 10-6 c/m2. (a) what is the magnitude of the electric field within the cell membrane? (b) find the magnitude of the electric force that would be exerted on a potassium ion (k+; charge = +e) placed inside the membrane.