Which term describes resistance to change in motion? A. acceleration

B. inertia

C. net force

D. velocity

Newton's second law of motion states that the accelaration of an object is directly proprotional to the force acting upon it. In symbols, we can write this as

Wher F is the force acting upon the object, m is the object's mass, and a is the object's acceleration. We can multiply both sides of this equation by 1/m to get the equivalent equation

What happens when we make m higher and higher? Well, that fraction 1/m gets closer and closer to zero. The same force accelarates the object less and less as that object becomes more massive. This consequence of Newton's second law, the resistance of massive objects to changes in acceleration, is called inertia, and it's one of the main expressions of mass in classical mechanics.