Question

an object is seen to either speed up, slow down, or change direction. what are these behaviors are caused by? unbalanced forces frictional force stable factors a balanced set of forces

Explanation:

According to Newton's first law of motion, an object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. When an object speeds up (accelerates), slows down (decelerates), or changes direction, its velocity (a vector quantity that includes speed and direction) is changing. A change in velocity means there is an acceleration. According to Newton's second law \(F = ma\) (where \(F\) is the net force, \(m\) is the mass, and \(a\) is the acceleration), an acceleration (\(a
eq0\)) implies that there is a non - zero net force. A non - zero net force is an unbalanced force.

Frictional force is a type of force, but it is not the only unbalanced force that can cause these changes. For example, a push or pull (other than friction) can also be the unbalanced force. Stable factors is a very vague term and not relevant in the context of forces causing motion changes. A balanced set of forces (\(\sum F=0\)) would result in no acceleration (\(a = 0\)), so the object would either remain at rest or move with a constant velocity (constant speed and direction).

Answer:

unbalanced forces