1. Physics 3 – Jan 10, 2017 P3 Challenge –
A thin spherical shell has a radius of 1.90 m. An applied torque of 950 Nm imparts to the shell an angular acceleration equal to rad/s2 about an axis through the center of the shell.
a) What is the moment of inertia of the shell?
b) Calculate the mass of the shell.
I = 2/3 MR2 for a thin shell.

2. Objectives/Agenda/Assignment
B.1 Rigid bodies and rotational dynamics
Agenda:
Review of Review questions for test
Assignment:
Study for Rotation test on Jan 12

3. Xtra Problem 1
A hemispherical sign 1.0 m in diameter and of uniform mass density is supported by two strings as shown. What is the tension in each string if the sign has a mass of 65.0 kg?

4. Xtra Problem Challenge!!
Sir Lost-a-Lot dons his armor and sets out from the castle on his trusty steed in his quest to rescue fair damsels from dragons. Unfortunately his aide lowered the drawbridge too far and finally stopped it 20.0° below the horizontal. Sir Lost-a-lot and his steed stop when their combined center of mass is 1.0 m from the end of the bridge. The bridge is 8.0 m long and has a mass of kg; the lift cable is attached to the bridge 5.0 m from the castle end and to a point 12.0 m above the bridge. Sir Lost's mass combined with his armor and steed is kg.
(a) Determine the tension in the cable and
(b) the horizontal and vertical force components acting on the bridge at the castle end.

5. Exit slip and homework
Exit Slip – A solid sphere with a mass of 2.5 kg and a radius of m is attached to a motor that applies a 450 N force at m. What force needs to be applied tangentially to the sphere to maintain a constant angular velocity? (I for solid sphere = 2/5 MR2)
What’s due? (homework for a homework check next class)
Study for the Test, Additional Review solutions are posted online
What’s next? (What to read to prepare for the next class)
Review for rotation test Jan 12 Thursday