We are now ready to start the study of rotation of rigid bodies.
To describe the motion of a rigid body, we need more than just the mass, we
need to know about
- Center of mass
- Momentum of inertia.
Sections 12.1 to 12.4
In this course we will not perform integrals like the one down in example
12.2, 12.5 and 12.6 so you can skip those problems although those skills will
be needed in Phys 212 for very similar problems.
The 3 stop to think questions are great and so are the other examples.
Worked Example on Center of Mass
Let me do one extra worked example from what is in the book. Imagine the
following situation.
An projectile (mass m_1) explodes at the top of its
trajectory (at x=x_0), breaking into two pieces – a small
piece, m_2, and a larger piece, m_3,
with m_3 = 2m_2 – which fly apart horizontally.
Surprisingly, the smaller piece falls back exactly at the launch site. Neglect
air resistance and effects due to the earth’s curvature.
How far away from the original launching point does the larger piece land?