Gravitation Jeopardy
Universal
Law of
Gravitation
Kepler’s
Laws
Astronomy
10
10
10
20
20
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30
30
30
40
40
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50
50
50
60
60
60
Circular
Motion
Part 1: Universal Law of
Gravitation
10 Points – ULG
Using Newton’s Universal Law of Gravitation, if
the mass of one of the objects increases by 5,
what happens to the force exerted between
them?
Answer
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10 Points Answer – ULG
• The force increases by 5.
Question
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20 Points - ULG
Using Newton’s Universal Law of Gravitation, if
the radius between the objects increases by 5,
what happens to the force exerted between
them?
Answer
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20 Points Answer – ULG
• The force decreases by 52
Or the force is 1/25 of the original force.
Question
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30 Points - ULG
Using Newton’s Universal Law of Gravitation, if
the radius between the objects decreases by
5, what happens to the force exerted between
them?
Answer
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30 Points Answer – ULG
• The force increases by 52
Or the force is 25 times the original force.
Question
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40 Points – ULG
• Determine the gravitational force exerted by
cookie monster on a nearby cookie.
– Mass of cookie monster: 200 kg
– Mass of cookie: 0.3 kg
– Distance between them: 5 m
– G: 6.67 x 10-11
Answer
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40 Points Answer – ULG
F = Gm1m2/r2
= (6.67x10-11)(200kg)(0.3kg)/(5m2)
= 1.6 x 10-10 N
Question
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50 Points – ULG
• Graph gravitational force versus the distance
between two objects
• How are these two physical quantities related?
–
–
–
–
Directly proportional
Directly proportional to the square of the distance
Inversely proportional
Inversely proportional to the square of the distance
Answer
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50 Points Answer – ULG
• How are these two physical
quantities related?
- Directly proportional
- Directly proportional to
the square of the
distance
- Inversely proportional
- Inversely proportional
to the square of the
distance
Question
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60 Points – ULG
• State Newton’s Law of Universal Gravitation.
Answer
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60 Points Answer – ULG
Fgrav = Gm1m2/r2
Gravitational force =
Gravitational constant*mass1*mass2/radius2
Question
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Part 2: Kepler’s Laws
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10 Points – Kepler
• What is Kepler’s First Law?
• What is at one focus?
Answer
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10 Points Answer – Kepler
Kepler’s First Law:
All planets orbit around the sun in an elliptical
shape.
The sun is at one focus.
Question
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20 Points – Kepler
• What is Kepler’s Second Law? What does it
tell you about the speed of an object in an
elliptical orbit?
Answer
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20 Points Answer – Kepler
• Objects sweep out equal areas in equal
amounts of time in their orbit
T1 = T2 if A1 = A2
• Objects travel faster when closer to the sun
Question
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30 Points – Kepler
• State Kepler’s Third Law. What ratio is equal
to Kepler’s constant for all bodies orbiting the
sun?
Answer
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30 Points Answer – Kepler
• The period squared divided by the semi-major
axis cubed is equal to Kepler’s constant.
• Kepler’s constant is equal to 1.
Question
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40 Points – Kepler
DOUBLE JEOPARDY!!!
• What does stellar retrograde motion depict?
• Why does Kepler’s First Law explain this
phenomena?
Answer
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40 Points Answer – Kepler
• Stellar retrograde motion is when stars or
planets appear to move backwards in the sky.
• We orbit the sun instead of all planets orbiting
us; therefore, if we pass another planet as we
circle the sun – it appears as though that
planet is travelling backwards.
Question
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50 Points – Kepler
Earth moves more slowly in its orbit
during June than during January. Is
Earth closer to the sun in June or in
January? What is the rationale for
your answer?
Answer
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50 Points Answer – Kepler
• Earth is closer to the sun in January. Since it
travels slower in June, that means the
gravitational pull is less which means Earth
must be farther away in June.
Question
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60 Points – Kepler
• Sketch the force and velocity arrows at each
point in this diagram.
Answer
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60 Points Answer – Kepler
Velocity arrows are red – always tangent to the ellipse
Force arrows are green – always pointed toward the focus
Question
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Part 3: Astronomy
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10 Points – Astronomy
• What are the two types of planets and what
are their main differences?
Answer
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10 Points Answer – Astronomy
• Terrestrial and Jovian
– Terrestrial are rocky planets
– Jovian are the gas giants
Question
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20 Points – Astronomy
• What are the criteria for being a planet?
Answer
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20 Points Answer – Astronomy
• Need to clear out the space in their orbit
• Need to be circular in shape
• Need to orbit the sun
Question
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30 Points – Astronomy
• How does the gravitational force exerted by
one planet in space on a second relate to the
force exerted by the second planet on the
first?
Answer
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30 Points Answer – Astronomy
• The forces are equal (Newton’s Third Law) and
opposite in direction.
Question
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40 Points – Astronomy
• List the planets around our sun in order.
Answer
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40 Points Answer – Astronomy
• Mercury, Venus, Earth, Mars
• Jupiter, Saturn, Uranus, Neptune
Question
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50 Points – Astronomy
• Explain what causes tides.
Answer
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50 Points Answer – Astronomy
• The moon pulls on each side of the Earth
differently, causing high tides on the side
closest to the moon and further away.
Question
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60 Points – Astronomy
• What are comets? What shape do their orbits
make? How does that help explain why
comets may not have originally been part of
the solar system?
Answer
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60 Points Answer – Astronomy
• Comets are balls of dust and ice.
• They orbit in very eccentric orbits (very oval
shapes) so they are not seen for very long
periods of time
• Because comets appear so irregularly,
astronomers were not able to chart their
course as easily as the other planets.
Question
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Part 1: Circular Motion
10 Points – CM
What direction is the acceleration for an object
spinning in a circle?
Answer
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10 Points Answer – CM
• Towards the center of the circle
Question
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20 Points - CM
Anna Litical is practicing a centripetal force
demonstration at home. She fills a bucket with
water, ties it to a strong rope, and spins it in a
circle. Why does the water not fall out?
Answer
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20 Points Answer – CM
• Inertia keeps the water moving in a straight
line, so the water “pushes against the back of
the bucket” keeping it from falling out.
Question
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30 Points - CM
A 900-kg car moving at 10 m/s takes a turn
around a circle with a radius of 25.0 m.
Determine the acceleration and the net force
acting upon the car.
Answer
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30 Points Answer – CM
TOK:
- m = 900kg
- v = 10 m/s
- r = 25.0 m
a = v2/r = 102/25 = 4 m/s2
F = ma = 900*4 = 3600 N
Question
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40 Points – CM
A tube is been placed upon the table and
shaped into a three-quarters circle. A golf ball
is pushed into the tube at one end at high
speed. The ball rolls through the tube and
exits at the opposite end. Describe the path of
the golf ball as it exits the tube.
Answer
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40 Points Answer – ULG
Will leave the
tube in the
direction it
was moving
already
(inertia)
Question
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50 Points – CM
• You want to make a bowling ball travel in a
circular counter-clockwise path around you (this
means YOU are the center point). After you set
the ball in motion “to the left”, in what direction
will force need to be exerted to keep the ball in a
circular path?
– You need to constantly push the ball away from you
– You need to constantly push the ball toward you.
– You need to constantly push the ball to the left
Answer
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50 Points Answer – CM
• You want to make a bowling ball travel in a
circular counter-clockwise path around you (this
means YOU are the center point). After you set
the ball in motion “to the left”, in what direction
will force need to be exerted to keep the ball in a
circular path?
– You need to constantly push the ball away from you
– You need to constantly push the ball toward you.
– You need to constantly push the ball to the left
Question
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60 Points – CM
Determine the centripetal force acting upon a
40-kg child who makes 10 revolutions around
the Cliffhanger in 29.3 seconds. The radius of
the barrel is 2.90 meters.
Answer
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60 Points Answer – CM
T = sec/rev = 29.3s/10rev = 2.93s
v = 2πr/T = 2π(2.90m)/2.93s = 6.2m/s
F = mv2/r = (40kg)(6.22 m/s)/(2.90m) = 533.4 N
Question
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Physics CP Jeopardy
Gravitation, Kepler’s Laws and
Astronomy Review
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