The earths magnetic field varies from point to point in space. Does it also change with time? If so, on what time scale does it change appreciably

Which statement is true? a. kepler's laws apply only to the motion of earth. b. kepler's laws can be used to predict eclipses. c. kepler's laws are true for a central force that is directly proportional to distance. d. kepler's laws can be deduced from newton's laws of motion and gravity.

Which of the following are considered noble gases? a. bromine b. neon c. argon d. chlorine

Suppose you increase your walking speed from 7 m/s to 13 m/s in a period of 2 s. what is your acceleration?