Question

A child rides the train at Disneyland which takes him in a loop around the amusement park at a speed of 3 m/s. Which statement best describes the child's motion on the train.

The velocity is changing because the direction is the same.

The velocity is the same because the speed is a constant.

The velocity is changing because the direction is changing.

The velocity is changing because the speed is the same.

Answer 1

A child rides the train at Disneyland which takes him in a loop around the amusement park at a speed of 3 m/s.

-- The speed is constant, because it's always 3 m/s.

-- The velocity is changing because the direction is changing. (This is one process that's called "acceleration". Th e others are speeding up and slowing down.)

-- Strange as it may seem, the AVERAGE velocity for one whole loop around the whole park is zero ! Because velocity uses the distance between the start-point and the end-point, no matter what the route is from start to finish, and the ride ends in the same place where it began, so the distance between the start-point and end-point is zero.

Answer 2

The velocity is a vectorial quantity, whereas speed is a scalar quantity, meaning it depends on the direction!
As such, the velocity is changing because the direction is changing.