The ptolemaic model of the universe describes the earth as

a. at the center, but moving relative to the other planets
b. at the center, stationary, with planets that rotate around it
c. orbiting around the sun with the other planets of our solar system
d. orbiting the moon, following the path of the sun

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?

Cells in the nervous system have a potential difference of 70 mv across the cell membrane separating the interior of the cell from the extracellular fluid. this potential difference is maintained by ion pumps that move charged ions across the membrane. is this an emf? select the correct answer and explanation. 1)no. the ion pumps cannot separate charges; thus, they cannot create a potential difference. 2)yes. the ion pumps cannot separate charges, but they still can create a potential difference. 3)yes. the ion pumps can actively separate charge; thus, they can create a potential difference. 4)no. the ion pumps can separate charges, but they cannot create a potential difference.

Ice at 0.0∘c has a density of 917 kg/m3. a 3.00 cm3 ice cube is gently released inside a small container filled with oil and is observed to be neutrally buoyant. what is the density of the oil?