1. Explain the meaning of "inverse square law".
2. Discuss each of Kepler's 3 laws.
3. At what point in its orbit is the Earth closest to the Sun?
4. At what point in its orbit is the Earth moving fastest?
5. What causes seasons?
6. What is a semi-major axis of orbit (a)?
7. What is an Astronomical Unit (AU)?
8. Consider Jupiter. It's orbit is 5 AU in size (roughly). How long should it take Jupiter to orbit the Sun once? Show how this calculation would be done.
9. What is the period of Earth's orbit around the Sun?
10. What is the size of Earth's orbit (in AU)?
11. When you stand on the Earth's surface, you experience your "normal" Earth weight. What would happen to your Earth weight if you were one Earth radius above the surface? (That's twice as far from the center as simply standing on the surface.)
12. What does gravitational force between 2 objects depend on?
13. Explain the Bernoulli principle, particularly as it is applied to flying things. What does the shape of an airfoil help accomplish?
(Answers below.)
General topics for exam 1. Be sure to review all assigned homework, blog posts and your notes.
You are permitted to have a sheet of notes for this test. I will NOT give equations.
pseudoscience
SI units (m, kg, s) - meanings, definitions
velocity
acceleration
related problems using the formulas
speed of light (c)
gravitational acceleration (g)
average vs. instantaneous velocity
freefall problems; using the equations of motion
Newton's 3 laws - applications and problems
Kepler's 3 laws - applications and problems
Newton's law of universal gravitation (inverse square law)
weight
the basics of flight
Relevant equations. Expect a few numerical problems - calculator should not be required.
v = d/t
a = (vf - vi)/t
or: vf = vi + at
d = vi t + 0.5 a t^2
F = m a
W = m g
a^3 = T^2
>
1. Explain the meaning of "inverse square law".
The force (of gravity, in this case) gets progressively weaker by the factor 1 over the distance squared. Double the distance --> force is 1/4 as great as it was. Triple the distance --> force is 1/9 the original.
2. Discuss each of Kepler's 3 laws.
See notes.
3. At what point in its orbit is the Earth closest to the Sun?
Perihelion, which is approximately January 3 each year.
4. At what point in its orbit is the Earth moving fastest?
Same point as 3 above.
5. What causes seasons?
Tilt of Earth's axis.
6. What is a semi-major axis of orbit (a)?
Half the longest distance across the orbital path (ellipse).
7. What is an Astronomical Unit (AU)?
Defined as the semi-major axis of Earth's orbit - roughly 93,000,000 miles - or half the longest width across Earth's orbit.
8. Consider Jupiter. It's orbit is 5 AU in size (roughly). How long should it take Jupiter to orbit the Sun once? Show how this calculation would be done.
5^3 = T^2
So, T = the square root of 125.
9. What is the period of Earth's orbit around the Sun?
1 year, or approximately 365.25 days.
10. What is the size of Earth's orbit (in AU)?
Defined as 1 AU.
11. When you stand on the Earth's surface, you experience your "normal" Earth weight. What would happen to your Earth weight if you were one Earth radius above the surface? (That's twice as far from the center as simply standing on the surface.)
1/4 your surface weight.
12. What does gravitational force between 2 objects depend on?
mass of the objects; distance between; a universal (unchanging) constant (G)
>
Earlier questions to review:
1. What are epicycles and why were they important? What is retrograde motion and what is *actually* going on when Mars seems to move backward?
You are permitted to have a sheet of notes for this test. I will NOT give equations.
pseudoscience
SI units (m, kg, s) - meanings, definitions
velocity
acceleration
related problems using the formulas
speed of light (c)
gravitational acceleration (g)
average vs. instantaneous velocity
freefall problems; using the equations of motion
Newton's 3 laws - applications and problems
Kepler's 3 laws - applications and problems
Newton's law of universal gravitation (inverse square law)
weight
the basics of flight
Relevant equations. Expect a few numerical problems - calculator should not be required.
v = d/t
a = (vf - vi)/t
or: vf = vi + at
d = vi t + 0.5 a t^2
F = m a
W = m g
a^3 = T^2
>
1. Explain the meaning of "inverse square law".
The force (of gravity, in this case) gets progressively weaker by the factor 1 over the distance squared. Double the distance --> force is 1/4 as great as it was. Triple the distance --> force is 1/9 the original.
2. Discuss each of Kepler's 3 laws.
See notes.
3. At what point in its orbit is the Earth closest to the Sun?
Perihelion, which is approximately January 3 each year.
4. At what point in its orbit is the Earth moving fastest?
Same point as 3 above.
5. What causes seasons?
Tilt of Earth's axis.
6. What is a semi-major axis of orbit (a)?
Half the longest distance across the orbital path (ellipse).
7. What is an Astronomical Unit (AU)?
Defined as the semi-major axis of Earth's orbit - roughly 93,000,000 miles - or half the longest width across Earth's orbit.
8. Consider Jupiter. It's orbit is 5 AU in size (roughly). How long should it take Jupiter to orbit the Sun once? Show how this calculation would be done.
5^3 = T^2
So, T = the square root of 125.
9. What is the period of Earth's orbit around the Sun?
1 year, or approximately 365.25 days.
10. What is the size of Earth's orbit (in AU)?
Defined as 1 AU.
11. When you stand on the Earth's surface, you experience your "normal" Earth weight. What would happen to your Earth weight if you were one Earth radius above the surface? (That's twice as far from the center as simply standing on the surface.)
1/4 your surface weight.
12. What does gravitational force between 2 objects depend on?
mass of the objects; distance between; a universal (unchanging) constant (G)
>
Earlier questions to review:
1. What are epicycles and why were they important? What is retrograde motion and what is *actually* going on when Mars seems to move backward?
2. What contributions did Galileo make with his telescope? What got him into trouble?
3. What is Copernicus' main contribution to science?
4. Know and understand the demonstrations with the "ball dropping and launching" cart.
5. Consider a ball falling for 3 seconds. Find the speed after 3 seconds of fall, and the distance this ball would fall (without air resistance).
6. A car starts from rest and accelerates for 5 seconds at 2 m/s/s. Find the speed after 5 seconds and the distance the car will travel in this time. (Note the similarity with the previous problem. Only the acceleration is different.)
>
1. Know and understand Newton's laws of motion.
5. Consider a ball falling for 3 seconds. Find the speed after 3 seconds of fall, and the distance this ball would fall (without air resistance).
6. A car starts from rest and accelerates for 5 seconds at 2 m/s/s. Find the speed after 5 seconds and the distance the car will travel in this time. (Note the similarity with the previous problem. Only the acceleration is different.)
>
1. Know and understand Newton's laws of motion.
2. A 10-kg object is pushed on by a 200-N force. What will be the acceleration?
3. What is the weight of a 100-kg man?
4. Would the answer to 3 be different if he was on the moon? How so?
5. Consider yourself standing on a scale in an elevator. The scale reads your weight. Compared to being at rest, how would the scale reading change (if at all) if the elevator were:
A. Moving with constant velocity upward
B. moving with constant velocity downward
C. Moving with constant acceleration upward
D. Moving with constant acceleration downward
E. If the cable snapped (yikes!) and the elevator were falling
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