A toy train moves with uniform speed on a circular track.Which of the following statements is true?
A)The angular acceleration is always positive.
B)The angular acceleration is always negative.
C)The angular acceleration can either be positive or negative,depending if the train runs clockwise or counter-clockwise.
D)The centripetal acceleration is 0.
E)The centripetal acceleration does not change in magnitude.

Question

Quizplus · Accepted Answer

Since the train moves with uniform speed, its velocity is constant in magnitude and direction. Therefore, the acceleration is entirely due to the centripetal acceleration, which points towards the center of the circular track. The magnitude of the centripetal acceleration is given by a = v^2/r, where v is the speed of the train and r is the radius of the track. Since both v and r are constant, the magnitude of the centripetal acceleration is also constant, and therefore, the best choice is E, which states that the centripetal acceleration does not change in magnitude. The other choices are incorrect because the angular acceleration is not necessarily constant or in a particular direction, and the centripetal acceleration is non-zero and constant.

A Toy Train Moves with Uniform Speed on a Circular