The bookshelf will move forward due to unbalanced forces.
A stationary object is acted upon by forces such as:
These forces must be overcome in order for an object to move.
Thus, if Kelley can apply a push force that will overcome and surpass all the forces acting on the bookshelf, the bookshelf will move forward.
Otherwise, it will stay still due to the forces mentioned above. In summary, the bookshelf will most likely move forward due to an unbalanced force.
More on forces can be found here: https://brainly.com/question/866413?referrer=searchResults