Question

A teacher uses the model that little invisible gremlins speed up or slow down objects and the direction they push gives the direction of acceleration. This is most similar to

Answer 1

Answer: Newton's second law.

Explanation: The rate of change of the velocity is called "acceleration"

The acceleration is defined by the second Newton's law, that says that the force applied on an object is equal to the mass of the aboject multiplied by the acceleration of the object:

F = m*a

Where the acceleration points in the same direction than the force applied.

So the model of the gremmlins is explaining this law.

Answer 2

Newton's second law describes how a net force is needed to accelerate an object.