What is defined as a push or pull that causes an object to change its motion?

The correct choice is force, which is defined as a push or pull that can cause an object to change its state of motion. This can result in the object speeding up, slowing down, or changing direction. In physics, force is a vector quantity, meaning it has both magnitude and direction, which is crucial in understanding how it influences the motion of objects.

Force is fundamentally related to Newton's Second Law of Motion, which states that the acceleration of an object is directly proportional to the net force acting upon it and inversely proportional to its mass. This relationship highlights how force is the primary agent that instigates change in an object's motion.

The other options, while related to motion in various ways, do not accurately capture the concept of a push or pull. Mass refers to the amount of matter in an object and does not involve the interaction that causes motion. Inertia is the property of an object that resists changes in its motion; it describes an object's tendency to maintain its state of motion but does not itself cause motion. Pressure is related to force applied over an area but does not define the action of causing motion directly.

Understanding force as a fundamental concept in mechanics is essential for further studies in physics and engineering, as it lays the groundwork