State Newton's second law of motion.
give one application along~

Newton 's second law of motion States That -

The time rate of change of the momentum of a body is equal in both magnitude and direction to the force imposed on it.

Rocket launch is an Example For it!.

Explanation:

Hope it helps!.

Newton's Second Law of Motion  states that the rate of change of momentum of a body is directly proportional to the applied force and takes place in the direction in which the force acts.

Explanation:

Application : -

Pushing or pulling an empty cart is easy as compared to a loaded cart

Reason,

the loaded cart has more mass. If the same amount of force is applied to move a car and a bike, the acceleration of the bike will be more because it has less mass than the car.

i think the answer is a, hope this is right, that would be my best guess.

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.