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MP 1 Science Quarterly Review
Earth’s orbit and seasons
1. What is the difference between rotation and revolution?
Earth rotates by spinning on its axis. One rotation takes 24 hours. Earth revolves
(or orbits) around the Sun. One revolution takes about 365 days.
2. What causes the apparent movement of the sun across the sky during the day on Earth?
The rotation of Earth to the East causes the sun to move across the sky as your
viewpoint turns toward the sun until noon then away until sundown.
3. What is the shape of a planet's orbit?
Planets orbit in elliptical (oval) orbits. The orbits become more circular over time
but never become a perfect circle.
4. How long does one complete revolution of Earth around the sun take?
Earth takes about 365 days to make a complete revolution.
5. What are the dates of the solstices and equinoxes in the Northern Hemisphere?
Vernal equinox- March 21; Summer solstice- June 21; Autumnal equinoxSeptember 23; Winter solstice- December 21/22.
6. What is the angle of Earth’s tilt?
About 23.5 degrees.
7. What would happen if Earth tipped over so that its axis was tilted 80 degrees?
At the solstices the poles would be pointed almost directly at the sun during the
summer. Summer temperatures would increase dramatically and much of the
hemisphere would experience 24 hours of daylight for much of the season. During
the winter the pole would be pointed almost directly away from the sun. Winter
temperatures would decrease dramatically with most of the hemisphere
experiencing 24 hours of night for much of the season. The only temperate areas
would be in the equatorial regions.
Newton’s Laws and Gravity
8. What are Newton’s 3 Laws of Motion?
1- An object at rest remains at rest and an object in motion will remain in motion (in
a straight line and at a constant speed) unless acted upon by an unbalanced force.
2- F=ma (Force=mass x acceleration)
3- For every action there is an equal and opposite reaction.
9. What two forces keep Earth is kept in orbit around the sun?
Inertia keeps Earth moving forward and gravity pulls the Sun and Earth toward each
other. The combination results in Earth following an elliptical orbit.
10.Why does a crumpled piece of paper hit the ground before a flat sheet of paper?
The flat piece of paper has a greater surface area so there is much more air
resistance to slow it down. The crumpled paper is more streamlined (aerodynamic)
so it falls more quickly. NOTE: in a vacuum both papers would fall at the same
speed.
11.What 2 factors affect gravity?
The mass of the objects and the distance (squared) between them (measured from
the centers of the objects).
12.Which of Newton’s Laws best describes a sled sliding on a flat, icy surface with a
constant velocity?
Inertia, the first law. An object in motion will remain in motion, in a straight line,
and at a constant velocity.
13.Why do you lean towards the left when a car turns right?
Inertia keeps you moving forward in the original direction while the car moves to
the right.
14.According to Newton’s first law of motion, what will happen to a moving object that is
not acted on by an unbalanced force?
It will continue to move in the same direction, in a straight line, and at a constant
speed.
Stars and the Universe
15.Approximately, how old is the Universe?
The Universe is approximately 13.8 billion years old.
16.What is a system of billions of stars, together with gas and dust, held together by
gravitational attraction called?
A galaxy.
17.What the most massive stars form when they collapse and die?
The most massive stars become black holes.
18.Define a light-year.
The distance light travels in a year, about 6 trillion miles, or 9.5 trillion kilometers.
19.What are the colors of the stars from coolest to hottest?
Red, Orange, Yellow, White, Blue
20.Understand what the Hertzsprung-Russell diagram shows, and be able to identify types of
stars on it.
The coolest stars are on the right side of the diagram and get hotter as you move
to the left. Smaller stars are on the bottom of the diagram and grow larger (and
more luminous) as you move up.
The Process of Science
21.Hypothesis has to be in an IF—THEN—BECAUSE format.
22.Independent variables are the IF (the cause). Dependent variables are the THEN (the
effect).
23.Controlled variables are those things that must be the SAME in both your experimental
and control group.
24.Observations are made using the 5 senses to describe something. Inferences are
conclusions you make based on observations.