Here's why:

* Velocity is the rate of change of an object's position. If an object is stationary, its position isn't changing, so its velocity is zero.

* Acceleration is the rate of change of an object's velocity. Since a stationary object has zero velocity, its acceleration is also zero.

It's important to note that a stationary object might still experience forces. These forces could be balanced, resulting in no net force and no movement. For example, a book sitting on a table experiences the force of gravity pulling it down, but it's balanced by the normal force from the table pushing it up.

However, even though the book isn't moving, it's still subject to forces. The forces are simply balanced, resulting in a net force of zero.