A2L Item 176

Goal: Problem solving with dynamics

Source: UMPERG-ctqpe135.3

A
disk, with radius 0.25 m and mass 4 kg, lies on a smooth
horizontal table. A string wound about the disk is pulled with a
force of 8N. What is the acceleration of the disk?

  1. 0
  2. 0.5 m/s2
  3. 1 m/s2
  4. 2 m/s2
  5. 4 m/s2
  6. None of the above.
  7. Cannot be determined

Commentary:

Answer

(4) Students find it difficult to grasp that the angular dynamic
relationship does not replace, but rather augments, the 2nd law.