Circular%20Motion%20Hot%20Seat

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Circular Motion Hot Seat
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1. The centripetal force on a car rounding a
curve on a level road is provided by
a) gravityb) frictionc) the engined) the
cars brakese) normal force
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2. On a banked turn, what is providing the
centripetal force on a car?

1. friction and tension
2. friction and gravity
3. friction and normal force
4. friction only

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3. The moons mass is only 1.2 of the earths
mass. Relative to the gravitational force the
earth exerts on the moon, the gravitational force
the moon exerts on the earth is
a) smallerb) the samec) greaterd) depends
on whether the moon is made of cheese or not
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4. The moons mass is only 1.2 of the earths
mass. The gravitational acceleration the earth
experiences compared to the gravitational
acceleration the moon experiences is

• smaller
• b) the same
• c) greater

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5. A bucket on a water wheel with a radius of
2.5 m makes one complete revolution in 4.2
seconds. How fast is the bucket moving?

• a)7.48 m/s
• b)3.7 m/s
• c)2.6 m/s
• d)1.87 m/s

v d/t d Circumference 2pr v 2p(2.5)/4.2 v
3.7 m/s
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6. A 0.5 kg ball moves in a circle 40 cm in
radius at a speed of 4.0 m/s. Its centripetal
acceleration is
F mv2/r ma mv2/r a v2/r a 42/.4 a 40
m/s2
a) 10 m/s2 b) 20 m/s2 c) 30 m/s2 d) 40 m/s2
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7. If the mass of Sputnik was doubled, by what
factor would the force change if it was to remain
in the same circular orbit?

1. two times greater
2. four times greater
3. half as much
4. one-fourth as much
5. no change

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8. Two small masses that are 10 cm apart attract
each other with a force of 10 N. When they are 5
cm apart, with what force will they attract each
other? (G 6.67 ? 10-11 Nm2/kg2)

• a) 5 N
• b) 2.5 N
• c) 20 N
• d) 40 N

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9. An object moves in a circular path. If the
radius is doubled while keeping the tangential
speed the same, then the centripetal force must
be
a) two times moreb) half as muchc) four
times mored) one-fourth as muche) the same
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10. A planet of mass 3 ? 1028 kg is in orbit
around a star with mass 3 ? 1030kg. The radius
of the orbit is 1.5 ? 1010m. The speed of the
planet in orbit is
a) 6.03 ? 1048 m/sb) 1.15 ? 1012 m/sc) 1.15 ?
104 m/sd) 1.16 ? 105 m/s
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11. The speed of the planet from the previous
question is 1.16 ? 105 m/s. What is the period
of the planets orbit?
a)8.12 ? 105 sb)4.21 ? 106 sc)3.23 ? 103
sd)2.74 ? 103 s
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12. The radius of the path of an object in
constant circular motion is doubled. The
centripetal force needed if its period remains
the same is
a) half as great as it was beforeb) the same as
beforec) twice as great as befored) four times
as great as before
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13. Consider a roller coaster doing a loop.
What provides the centripetal force?

• Friction
• Normal force
• Tension
• Gravity

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14. Consider a roller coaster at the top of a
loop. What provides the centripetal force?

• Friction and Gravity
• Normal force and Friction
• Tension and Normal Force
• Gravity and Normal Force
• Centripetal Force and Gravity