Which of the following best describes the origin of ocean tides on Earth?
A) Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth.
B) The Moon's gravity pulls harder on water than on land, because water is less dense than rock.
C) Tides are caused by the 23 1/2 tilt of the earth's rotational axis to the ecliptic plane.
D) Tides are caused primarily by the gravitational force of the Sun.
E) Tides are caused on the side of Earth nearest the Moon because the Moon's gravity attracts the water.
Question 2
In relativity, two people share the same frame of reference only if
A) they are not moving relative to each other.
B) they are both located in the same place.
C) they are both located in the same place and are traveling at the same speed.
D) they are both located in the same place and are stationary.
E) they agree on the laws of nature.
Changes in Earth's atmospheric carbon dioxide levels over geological time.
Possible Earth 5 billion years from now
Origin of T cells, B cells, RBCs, WBCs, and platelets.
Ocean-view
Muscle weakness caused by myasthenia gravis is evident in the eyes of this patient.
Earth’s Spheres