Category: Force and Motion

The rest of this chapter consists of sample problems. You should pore over them, learning not just their particular answers but, instead, the procedures they show for attacking a problem. Especially important is knowing how to translate a sketch of a situation into a free-body diagram with appropriate axes, so that Newton’s laws can be…

The Gravitational Force A gravitational force  on a body is a certain type of pull that is directed toward a second body. In these early chapters, we do not discuss the nature of this force and usually consider situations in which the second body is Earth. Thus, when we speak of the gravitational force  on a body, we usually mean…

All the definitions, experiments, and observations we have discussed so far can be summarized in one neat statement:  Newton’s Second Law: The net force on a body is equal to the product of the body’s mass and its acceleration. In equation form, This equation is simple, but we must use it cautiously. First, we must be…

Everyday experience tells us that a given force produces different magnitudes of acceleration for different bodies. Put a baseball and a bowling ball on the floor and give both the same sharp kick. Even if you don’t actually do this, you know the result: The baseball receives a noticeably larger acceleration than the bowling ball.…

We now wish to define the unit of force. We know that a force can cause the acceleration of a body. Thus, we shall define the unit of force in terms of the acceleration that a force gives to a standard reference body, which we take to be the standard kilogram of Fig. 1-4. This body has…

Before Newton formulated his mechanics, it was thought that some influence, a “force,” was needed to keep a body moving at constant velocity. Similarly, a body was thought to be in its “natural state” when it was at rest. For a body to move with constant velocity, it seemingly had to be propelled in some…

The relation between a force and the acceleration it causes was first understood by Isaac Newton (1642–1727) and is the subject of this chapter. The study of that relation, as Newton presented it, is called Newtonian mechanics. We shall focus on its three primary laws of motion. Newtonian mechanics does not apply to all situations. If the…

We have seen that part of physics is a study of motion, including accelerations, which are changes in velocities. Physics is also a study of what can cause an object to accelerate. That cause is a force, which is, loosely speaking, a push or pull on the object. The force is said to act on the object to change its…