Goal: Reasoning with circular motion
Source: UMPERG-ctqpe37
A small ball is released from rest at position A and rolls down a
vertical circular track under the influence of gravity.
![](/files/Item133_fig1.gif)
When
the ball reaches position B, which of the indicated directions most
nearly corresponds to the direction of the ball’s acceleration?
Enter (9) if the direction cannot be determined.
Commentary:
Answer
(2) At position B the acceleration has a tangential component and
a radial component. Both components can be determined at position B.
Worked out carefully one gets 18 degrees above position #2. It is common
for students to neglect one component or the other.