Eratosthenes measured the circumference of Earth to within 4% of the correct value Eratosthenes measured the circumference of Earth to within 4% of the correct value noting how much more of the celestial sphere came into view when walking south. using the detailed reports of far-sailing mariners. looking at stick shadows on the solstice. sighting the stars from within the deepest well in Egypt on the day of the solstice.

Note: the following questions are unrelated to the balmer series or the martian. refer to your course notes. a sun-sized star will spend most of its lifetime as a: white dwarf b. red giant c. protostar d. main-sequence star

A3.9 g aluminum foil ball with a charge of +4.1×10−9 c is suspended on a string in a uniform horizontal e⃗ field. the string deviates to the right and makes an angle of 30∘ with the vertical. part a part complete what information about the e⃗ field can you determine for this situation? what information about the field can you determine for this situation? only the magnitude of e⃗ only the direction of e⃗ both the magnitude and the direction of e⃗ none of the above previous answers correct part b determine the magnitude of the electric field. express your answer with the appropriate units. e e = nothing nothing request answer part c determine the direction of the electric field. determine the direction of the electric field. to the right to the left away from you toward you

If an electric circuit is not grounded it is best to reach out and touch it to provide the ground a.true or b.false