Considering the momentum equation, a force causes a change in velocity; and likewise, a change in velocity generates a force. The equation works both ways. The velocity, force, acceleration, and momentum have both a magnitude and a direction associated with them.
Scientists and mathematicians call this a vector quantity. The equations shown here are actually vector equations and can be applied in each of the component directions. We have only looked at one direction, and, in general, an object moves in all three directions up-down, left-right, forward-back. His third law states that for every action force in nature there is an equal and opposite reaction. If object A exerts a force on object B, object B also exerts an equal and opposite force on object A.
In other words, forces result from interactions. An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force. The acceleration of an object depends on the mass of the object and the amount of force applied.
Whenever one object exerts a force on another object, the second object exerts an equal and opposite on the first. Examples of inertia involving aerodynamics: The motion of an airplane when a pilot changes the throttle setting of an engine. The motion of a ball falling down through the atmosphere. Have you ever observed the behavior of coffee in a coffee cup filled to the rim while starting a car from rest or while bringing a car to rest from a state of motion? Coffee "keeps on doing what it is doing.
While the car accelerates forward, the coffee remains in the same position; subsequently, the car accelerates out from under the coffee and the coffee spills in your lap. On the other hand, when braking from a state of motion the coffee continues forward with the same speed and in the same direction , ultimately hitting the windshield or the dash.
Coffee in motion stays in motion. Have you ever experienced inertia resisting changes in your state of motion in an automobile while it is braking to a stop? The force of the road on the locked wheels provides the unbalanced force to change the car's state of motion, yet there is no unbalanced force to change your own state of motion.
Thus, you continue in motion, sliding along the seat in forward motion. A person in motion stays in motion with the same speed and in the same direction Seat belts are used to provide safety for passengers whose motion is governed by Newton's laws. The seat belt provides the unbalanced force that brings you from a state of motion to a state of rest.
Perhaps you could speculate what would occur when no seat belt is used. There are many more applications of Newton's first law of motion. Several applications are listed below.
Perhaps you could think about the law of inertia and provide explanations for each application. Acquire a metal coat hanger for which you have permission to destroy. Pull the coat hanger apart. Therefore, the first law says that the velocity of an object remains constant if the net force on it is zero.
It provides a method for identifying a special type of reference frame: the inertial reference frame. In principle, we can make the net force on a body zero. If its velocity relative to a given frame is constant, then that frame is said to be inertial.
From this fact, we can infer the following statement. A reference frame moving at constant velocity relative to an inertial frame is also inertial. A reference frame accelerating relative to an inertial frame is not inertial.
Are inertial frames common in nature? All frames moving uniformly with respect to this fixed-star frame are also inertial. For example, a nonrotating reference frame attached to the Sun is, for all practical purposes, inertial, because its velocity relative to the fixed stars does not vary by more than one part in 10 Earth accelerates relative to the fixed stars because it rotates on its axis and revolves around the Sun; hence, a reference frame attached to its surface is not inertial.
Thus, unless indicated otherwise, we consider reference frames fixed on Earth to be inertial. Finally, no particular inertial frame is more special than any other. As far as the laws of nature are concerned, all inertial frames are equivalent. In analyzing a problem, we choose one inertial frame over another simply on the basis of convenience. Returning to Forces and the ice skaters in Figure 5.
To create equilibrium, we require a balancing force that will produce a net force of zero. See the free-body diagram in Figure 5.
If a car is at rest, the only forces acting on the car are weight and the contact force of the pavement pushing up on the car Figure 5. It is easy to understand that a nonzero net force is required to change the state of motion of the car. As a car moves with constant velocity, the friction force propels the car forward and opposes the drag force against it. Why or why not? A skydiver opens his parachute, and shortly thereafter, he is moving at constant velocity. Explain the effects with the help of a free-body diagram.
Use free-body diagrams to draw position, velocity, acceleration, and force graphs, and vice versa. Explain how the graphs relate to one another. Given a scenario or a graph, sketch all four graphs. As an Amazon Associate we earn from qualifying purchases.
Want to cite, share, or modify this book?
0コメント