Download Online STUDY QUESTIONS #8 — ANSWERS 1. Mercury moves

Online STUDY QUESTIONS #8 — ANSWERS
1. Mercury moves fastest when it is closest to the sun and slowest when farthest from the sun.
2. P 2 = D3
and so,
P = D3 = 0.4 3 = 0.25 earth years
3. Parallax is the shift of a close object relative to the far background.
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4. Star #1 is closest to us, star #3 is farther than #1 since it shifts only a little bit, and star #2 is too far to
tell (since it does not shift)
5. A parsec is a unit of measurement based on the distance of a star that subtends an angle of 1 arcsec
with the radius of the earth's orbit as a baseline. It is equal to about 3.26 light-years.
6. According to Kepler's first law, the orbits of the planets are in the shape of
a. a cone
b. an ellipse
c. a circle
d. an irregular loop
7. It moves fastest when closest to the sun, slowest when farthest from the sun.
8. According to Kepler, the star must lie at one of the focus points of the ellipse. Here I have drawn the
star on the right focus point, but you could have put it on the left one.
9. Inertia is a property of matter that represents the amount of resistance to a change of motion. The
amount of intertia is proportional to the amount of mass an object has.
10. Yes, because you have changed direction
11. Velocity is speed with direction. Acceleration is a change of velocity.
12. Yes. Because you have changed your speed
13. Due to the pendant's inertia, the pendant will try to keep its position. Your hand at the top of the chain
moves forward as the car does, and so the pendant appears to swing backwards toward you.
14. At constant speed and direction (constant velocity), there are no forces on the pendant other than
gravity and so it will point to the center of the Earth.
15. Due to the pendant's inertia, the pendant will try to keep its position, pointing toward the center of the
Earth. The change in speed, however, causes your hand at the top of the chain to move backward as
the car does and so the pendant appears to move forward away from you.
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17. The earth accelerates you more than you accelerate the earth, yet the force you exert on each other is
exactly the same. The reason is that the earth is *very* massive and you are not!
you are not as massive as the earth
the forces are equal
m you a you = F earth on you
=
Fyou on the earth = Mearth aearth
so the accelerations are not equal
18. Star B is closest to us. Both stars had the same parallax shift, but star A had this shift with a greater
baseline (orbit of earth) than the observation of star B (baseline of the diameter of earth).
19. If you draw the star to be on the right focus point, then looking behind would give you the view:
Instead of going counterclockwise around its star, the planet would appear to be going clockwise and the
star would appear to be located at the other focus point.