(a)

The particle speeds up when the velocity is positive and increasing.

Thus, from the graph it happens in the interval .

The particle is also speeds up when the velocity is negative and decreasing.

Thus, from the graph it happens in the interval .

The particle slows down when the velocity is positive and decreasing.

Thus, from the graph it happens in the interval .

(b)

The particle speeds up when the velocity is positive and increasing.

Thus, from the graph it happens in the interval .

The particle is also speeds up when the velocity is negative and decreasing.

Thus, from the graph it happens in the interval .

The particle slows down when the velocity is positive and decreasing.

Thus, from the graph it happens in the interval .

The particle is also slows down when the velocity is positive and decreasing.

Thus, from the graph it happens in the interval .

(a) The particle speeds up when or and slows down when .

(b) The particle speeds up when or and slows down when or .