For the quiz, unless otherwise mentioned, assume the frictional torque is zero.
1. The rod connecting the 10Kg and 5Kg end is very light.
The Inertial of the system will be greatest when
rotated around point________.
a. A
b. B
c. C
d. D
e. E
2.
The rear wheels of two seperate bicycles, A and B,
each have their chains moving at the same speed
(relative to the bike). The world places the same
frictional torque on both bikes. Bike A is moving at a
speed ________ Bike B. The tension required to pull
the chain in Bike A is __________ the tension
required to pull the top of the chain in Bike B.
(assume the bottom chain applies neglidgible torque
in both)
a. Equal to, less than
b. Greater than, greater than
c. Greater than, less than
d. Less than, greater than
e. Less than, less than
3.
The following objects are rolled up a plane with the same speed. Which will likely reach the highest point
on the plane? (assume all items will behave ideally)
a. Bouncy ball (solid)
b. marble
c. Tennis Ball
d. Pop can (filled with pop)
e. Ring (hollow)
4.
What is the net torque applied by the system?
a. 6Nm
b. 9Nm
c. 15Nm
d. 21Nm
e. 27Nm
5. The angular velocity of a spinning object changes according to the function ω=48t-6t2. When
will the angular acceleration be zero?
a. 0s
b. 4s
c. 8s
d. 12s
e. 16s
6.
Mass M strikes the rod of negligible mass and sticks. A mass of 2m is
secured half way down the rod. The vertical rod on the right is strictly
there as a support; it is not attached to the horizontal bar. The mass is
moving at speed v at impact. The rod is free to rotate without restraint
around the left side. The instant after the collision, the linear speed of the
mass m will be__________.
a. (1/4)v
b. (1/3)v
c. (1/2)v
d. (2/3)v
e. (3/4)v
7.
A bar is secure but free to rotate around the left side. Gravity is present. Strings could be placed in
positions and with the orientations indicated in (a-e). Which string could support the bar with the least
tension?
8.
Two identical stars of mass M are separated by a distance D. The stars rotate around each other in
perfect circles. The speed of each star is V. If the stars were instead separated by a distance of 4D, the
speed would need to be _______________ to maintain circular paths?
a. .25V
b. .5V
c. V
d. 2V
e. 4V
9.
A spool is hung from two strings connected to a platform. The platform is securely fixed to the ceiling.
The spool has a mass of m and the platform has a mass of M. The string on the left is at radius R, while
the string on the right is at radius .5R, all relative to the center of the uniform spool. The inertia of the
spool, when rotated about its center of mass, is I=.5mR2. Solve each of the following in terms of given
variables and fundamental constants. (mass M and m are not equal)
a)
Determine the force the ceiling must exert to support the system.
b)
Determine the tension on
i.
The left string
ii.
The right string
The string on the right is now cut, as shown, allowing the system to
fall, supported by the single string, unspooling as the system falls.
c)
d)
e)
Determine the linear acceleration of the spool
Determine the tension on the lone string
Determine the force the ceiling must exert on the system as the spool falls