A2L Item 107

Goal: Reason with the concept of moment of inertia

Source: UMPERG-ctqpe116

The rotational inertia of the dumbbell (see figure) about axis A is
twice the rotational inertia about axis B. The unknown mass is

  1. 2 kg
  2. 4 kg
  3. 5 kg
  4. 7 kg
  5. 10 kg
  6. None of the above
  7. Cannot be determined



(4) Students can get bogged down in calculations when it is unnecessary
to do detailed calculations. Proportional distances to the axes is all
that is needed. This problem presents a good opportunity to discuss
problem solving procedures.