Why is it so difficult to study the center of our galaxy?
a. Light from the center is lost in the glow of emission nebulae in this direction.
b. Interstellar dust blocks almost all light before it reaches Earth.
c. The exact position of the center is not known.
d. The center of the galaxy puts out very little radiation and is too dim to study.
e. The center of the galaxy is too far away for radiation to be detected by telescopes.
Question 2
Newton's law of gravitational force states that ____.
a. an object with no force on acting on it continues at rest or moves in uniform motion in a straight line with constant velocity
b. an object with no force on it moves in a straight line with constant acceleration
c. for every action, there is an equal and opposite reaction
d. the force between two objects is directly proportional to the product of their masses and inversely proportional to the distance between them squared
e. an object with a force on it is accelerated in the direction of the force an amount inversely proportional to its mass and directly proportional to the size of the force
The light produced by fireflies is the result of a reaction
Light penetration in Rivers
Light
Testing the corneal light reflex
The results from West and Crook's study of memory for telephone numbers
In the retina, there are two types of light receptor cells: Rods are sensitive to differences in lig