1. Unit 6: Rotational Motion
ABCD Review
“It’s for prizes, yo!”

2. The variable s is used to represent:
angular displacement
arc length
tangential distance
radial distance

3. All of the following are good reasons to use radians instead of degrees when describing circular motion except:
degrees can’t be negatives
the geometry of circles is already in radians.
easier to express multiple rotations in radians.
when using degrees the numbers can get very large very quickly.

4. Omega is measured in ___________
rad/s2
m/s
m/s2
rad/s

5. A merry-go-round spinning at a constant speed has _______________
tangential acceleration but no centripetal acceleration
centripetal acceleration but no tangential acceleration
both tangential and centripetal acceleration
it’s impossible to tell

6. The units of radians are __________
none
degrees
meters π

7. Centrifugal force is ________________
a force directed toward the center
a force directed along the tangential path
the effects of Newton’s 1st Law
a combination of inertia and gravity

8. Centripetal acceleration is measured in
m/s
m/s2
rad/s
rad/s2

9. A child pedals her bicycle to go faster and faster
A child pedals her bicycle to go faster and faster. The wheels have _____________
tangential acceleration but no centripetal acceleration
centripetal acceleration but no tangential acceleration
both tangential and centripetal acceleration
it’s impossible to tell.

10. The units of alpha are ____________
rad/s
m/s
m/s2
rad/s2

11. As the Earth spins, which people experience the greatest tangential velocity?
Santa’s elves (North pole)
North Koreans (in North Korea)
Peruvians (in Peru)
New Zealanders (In New Zealand)

13. If an object has both tangential and centripetal acceleration, then it’s total acceleration is ____________
the sum of both
the difference between them
found using the Pythagorean Theorem
it depends on the direction of each

14. A space station spins as in the diagram below in order to create artificial gravity. Which picture shows how the people living inside will live? D A B C

15. Which of the following is an incorrect circular motion equation?
ωf2 = ωI2 + 2αθ
θ = ωIt + αt2
α = (ωf – ωi)/ t
They’re all correct

16. Where on Earth do objects fall the fastest?
a) at the equator
b) at either the north or south poles
c) halfway between the equator and the poles
d) they fall at the same rate everywhere

17. A person standing directly on the South Pole (rotational, not magnetic) has ________
equal amounts of alpha and omega
alpha but not omega
neither omega or alpha
more alpha than omega

18. A kid is sitting on a merry-go-round while his friend spins it faster and faster. The moment the kid flies off the ride:
the centripetal force was equal to the force of gravity
the centrifugal force was equal to the force of kinetic friction
the centripetal force was equal to the force of static friction
the centrifugal force was equal to the force of static friction

19. A kid is sitting on a merry-go-round while his friend spins it faster and faster. The moment the kid flies off the ride, the angular velocity is equal to:
the square root of (μsg)/r
mg + μsFN
mμsgrα
(gr)/mμs

20. Imagine a bicycle wheel with two beads on a spoke
Imagine a bicycle wheel with two beads on a spoke. One bead is very close to the center and the other bead is close to the rim. The wheel is rolling down a hill. Which of the following statements is NOT true?
a) Both beads experience the same angular velocity and angular accelerations
b) The tangential velocity is increasing for both beads but at different rates
c) The tangential acceleration of the bead near the rim is always higher than the bead near the center
d) The ratio of the two bead’s tangential velocities is a constant