1 Two discs of unequal mass and unequal radii are released from rest from the same height on an inclined plane. They roll without slipping.
Which of the following statements is correct?
a The larger more massive disc reaches the bottom first.
b The smaller less massive disc reaches the bottom first.
c Both discs reach the bottom at the same time.
d The discs would reach the bottom at the same time only if their masses and their radii were the same.
2 Two bottles of water, of the same volume, one frozen and one liquid, are released on a uniform rough incline, from the same height, at the same time. They roll without slipping.
Which of the following statements is correct?
a The liquid-water bottle reaches the bottom first because it is heavier.
b The frozen-water bottle reaches the bottom first because it has a smaller moment of inertia about its central axis.
c Both bottles reach the bottom at the same time because they have the same radius.
d The liquid water bottle reaches the bottom first because less potential energy is converted to rotational kinetic energy.
3 Two plastic wheels mounted on identical plastic axles axle roll without slipping on inclined rails. The radius of each wheel is the same. Wheel A has no rim. Wheel B has a flat extended rim.
Which of the following statements is correct?
a Both wheels roll with the same angular acceleration because the radii are identical.
b Wheel A has the greater angular acceleration because is has the lower moment of inertia.
c Wheel B has the lower angular acceleration because it has greater mass.
d Both wheels roll with the same angular acceleration because the only accelerating force is the force due to gravity which is constant.
4 A hollow pipe of radius r, mass m, rolls without slipping down an incline [with the axis perpendicular to the line of steepest descent].
The accelerating torque is given by ...
a ... (mg/r) sinq
b ... (mg/r) cosq
c ... mgr sinq
d ... mg/r cosq
5 Two equal masses descend from rest, from a height h, on two inclined planes. The block slides without friction, the sphere rolls without slipping.
Which of the following statements is correct?
a Both reach the bottom at the same time because they begin with the same potential energy.
b Both reach the bottom at the same time because they have the same mass and final kinetic energy.
c The sphere reaches the bottom first because it has the lower moment of inertia.
d The block reaches the bottom first.
6 A Japanese 5 Yen coin has a hole in the middle.
When approximating the moment of inertia of the coin about an axis through the center of mass, perpendicular to the disc, there are three alternatives....
I - the coin is considered to be a uniform disc.
II - the coin is considered to be a hoop.
III - the coin is considered to be uniform disc of the outside diameter minus a uniform disc of the inner diameter.
Which of the following statements is best.
a I is the best approximation because the hole has little effect.
b II is the best approximation because the moment of inertia of a hoop is easily found.
c III is the best alternative because it is the most accurate of the three.
d All three alternatives are equally good.
Question: Aya Sato
*7 A self retracting tape winds itself up.
Write a short essay describing the physical changes which are shown in the clip.
You will need to describe ...
... torque
... reaction torque
... angular momentum
... moment of inertia
Pay particular attention to the part played by friction between the case and thee floor during each stage of the motion.
Question: Seamus Jacobs