Newton’s Laws of Motion

Forces affect every moment of our life. Our bodies are held to the Earth by force, and they are held together by the forces of charged particles. When we …

In most situations, forces can be grouped into two categories: contact forces and field forces.  Contact forces occur as a result of direct physical …

Motion draws our attention. Motion itself can be beautiful, causing us to marvel at the forces needed to create spectacular sights, such as that of a …

Experience suggests that an object at rest remains at rest if left alone, and that an object in motion tends to slow down and stop unless some effort is …

Newton's first law states that a net external force causes a change in motion. External forces act on an object or system, originating outside of the …

Newton's second law is closely related to his first law of motion. It mathematically gives the cause-and-effect relationship between force and changes …

Mass and weight are often used interchangeably in everyday conversation. For example,  medical records often show our weight in kilograms, but never …

When an object is dropped, it accelerates toward the center of the Earth. If the net external force on the object is its weight, it is said to be in free …

Whenever one body exerts a force on a second body, the first body experiences a force equal in magnitude and opposite in direction, to the force that it …

Newton's third law states that every action has an equal and opposite reaction. Consider a swimmer pushing off the side of a pool. They push against …

The first step in describing and analyzing most phenomena in physics involves the careful drawing of a free-body diagram. Free-body diagrams are useful in …

Solving problems that involve forces is easy using free-body diagrams. A free-body diagram is a sketch showing all the external forces that are acting on …

Newton’s first law is usually considered to be a statement about reference frames. It provides a method for identifying a special type of reference …

A reference frame accelerating or decelerating relative to an inertial frame is a non-inertial frame. To help understand this, consider what taking off in …

True weight is the measure of the gravitational force acting on an object. However, if the object accelerates, its measured weight is different from its …

Pseudo forces, or fictitious forces, appear to act on an object in motion in a rotating frame of reference with respect to an inertial reference frame. …