spinning summary

1) __________________ determines how hard it is to make something spin, and _________________ determines how hard it is to make something stop spinning.

2) A washing machine for clothes eliminates the water from the clothes by spinning quickly. Two questions: (a) draw a picture of the water leaving the spinning tub, (b) explain the physics of the escaping water from the reference of the tub.

3) A spinning thing spins at 3.50
rad/sec. If it were accelerating at 0.55 rad/sec^{2}, what angular
distance must it move until it is spinning at 5.75 rad/sec?

4) Yet another spinning thing
accelerates at 0.25 rad/s^{2}. It continues accelerating at this rate
until it has swept a 1.90 rad angle. The movement took 1.75 sec. What was its
original angular speed?

5) If you were standing on a spinning disc, 1.5 m from its axis and moving at 4.4 m/s, what would be your angular velocity?

6) A 3.0 kg rock is twirled in a horizontal circular orbit at the end of a string of length 2.5 m. The rock makes 3.0 revolutions in 5.0 seconds. What is the tension in the string?

7) Remember the work-energy
theorem? (If not, *Work = **Δ**KE*.) Apply a
torque of 38 Nm to an object with a moment of 66 kgm^{2}. If you
applied the torque over an angle of 12 radians, what would be its angular
speed?

8) A torque is applied to a solid sphere –
perpendicular to its radius – causing it to accelerate. If the force applied is
140 N, what is its angular acceleration? The mass of the sphere is 8.5 kg, its
radius is 1.5 m, and its moment of inertia is (2/5)MR^{2}.

9) The moment of inertia for
a hollow sphere is (2/3)MR^{2}. Take a 14 kg sphere and apply a 85 N
force perpendicular to its 1.5 m radius. If it starts at rest, how many radians
will it spin in 4.4 seconds?

10) A car turns a circular corner
with a centripetal acceleration of 1.30 m/s^{2} while slowing from
7.5 m/s to 2.8 m/s in 2.3 s. What is the magnitude of the car’s total
acceleration?