Question

Which situation is contrary to Newton’s first law of motion? An object at rest begins to move when an external force is applied. A moving object has a constant velocity under the influence of balanced forces. An object at rest stays at rest as long as unbalanced forces act on it. A moving object slows down when an external force is applied.

Answer 1

Newton's first law establishes the following:

An object will remain at rest or with uniform rectilinear motion unless an external force acts on it.

Therefore, we have that a case contrary to Newton's first law is:

Unbalanced forces acting on an object at rest, cause the object to remain at rest.

It is false, because if the forces are unbalanced, then the object will not remain at rest because external forces act on the object.

Answer:

A situation that is contrary to Newton's first law of motion is:

An object at rest stays at rest as long as unbalanced forces act on it.

Answer 2

C. An object at rest stays at rest as long as unbalanced forces act on it.