Final answer:
The subject of motion in physics involves understanding the interactions between objects and forces, characterized by pushes or pulls which are vector quantities. It's essential to consider the direction and magnitude of motion, external forces such as friction and gravity, and concepts like inertia and equilibrium.
Step-by-step explanation:
To understand motion, you have to figure out if you're pushing on objects or things are pushing on you. Dynamics is the branch of physics that studies how forces affect the motion of objects and systems. A force is essentially a push or a pull with both magnitude and direction, making it a vector quantity. Examples of forces include the push of a person against a box or Earth's gravitational pull on objects. Understanding motion requires considering whether the object is in motion, whether it is moving in a positive or negative direction, or at rest, and assessing the external factors such as pressure and volume that can cause matter to move against opposing forces.
Dynamics also includes the study of Newton's Laws of Motion, which articulate how forces lead to changes in an object's motion. For instance, Newton's First Law, also known as the law of inertia, states that there must be a cause for any change in velocity, whether in magnitude or direction. Hence, equilibrium, friction, and the principle of inertia are important aspects in understanding the effects of force and motion.
It should also be noted that kinematics is the description of motion without considering its causes, differentiating it from dynamics. The effects of forces on objects are often represented through free-body diagrams, allowing an easier visual representation of forces acting upon a body and the resultant motion. Additionally, the concept of work is relevant when discussing motion as it involves forces causing displacement, such as pushing a box across a floor with varying levels of friction.