Moving that particle

Suppose a particle moves back and forth along a straight line with velocity $v(t)$ , measured in feet per second, and acceleration $a(t)$ . What are the meanings of the following $\displaystyle\int_{0}^{30}v(t)dt$ , $\displaystyle\int_{0}^{30}|v(t)|dt$ , and $\displaystyle v(t)|_{0}^{30}$ .

The terms used here are the following:

Displacement: of the particle measured in feet after travelling from 0 to 30 seconds.

Change in speed: of the particle measured in feet per seconds.

Distance: Total distance travelled by the particle in feet.