Question

What are the three ways that an object can accelerate

Answer 1

There are three ways an object can accelerate: a change in velocity, a change in direction, or a change in both velocity and direction.

Answer 2

An object can only accelerate when the forces acting on it are unbalanced.  

When that happens ...

-- the object's speed increases, OR

-- its speed decreases, OR

-- the direction of its motion changes.