How does an objects inertia cause it to behave

Picture two balls of different mass, traveling in the same direction at the same velocity. If they both collide with a wall at the same time, the heavier ball will exert a larger force on the wall.

It states: the net force on an object is equal to the rate of change of its linear momentum. From calculus we know that the rate of change is the same as a derivative. When we the linear momentum of an object we get:.

Force and Mass : This animation demonstrates the connection between force and mass. As we stated earlier, acceleration is the rate of change of velocity, or velocity divided by time. Sir Isaac Newton was a scientist from England who was interested in the motion of objects under various conditions. In , he published a work called Philosophiae Naturalis Principla Mathematica , which contained his three laws of motion.

These laws form the bases for mechanics. The laws describe the relationship between forces acting on a body, and the motion is an experience due to these forces. If object A exerts a force on object B, because of the law of symmetry, object B will exert a force on object A that is equal to the force acted on it:. In this example, F A is the action and F B is the reaction. You have undoubtedly witnessed this law of motion.

For example, take a swimmer who uses her feet to push off the wall in order to gain speed. The more force she exerts on the wall, the harder she pushes off. This is because the wall exerts the same force on her that she forces on it. She pushes the wall in the direction behind her, therefore the wall will exert a force on her that is in the direction in front of her and propel her forward. Take as another example, the concept of thrust. When a rocket launches into outer space, it expels gas backward at a high velocity.

The rocket exerts a large backward force on the gas, and the gas exerts and equal and opposite reaction force forward on the rocket, causing it to launch. This force is called thrust. Thrust is used in cars and planes as well. Then ask her why things can move if every force has a paired opposite force all the time, forever. Privacy Policy. Skip to main content. The Laws of Motion. Search for:. Galileo's experiments showed that all bodies accelerate at the same rate regardless of size or mass.

Newton also critiqued and expanded on the work of Rene Descartes, who also published a set of laws of nature in , two years after Newton was born. Descartes' laws are very similar to Newton's first law of motion. Back then, most people believed that the natural state of a body was to be at rest.

It was obvious that imparting motion to a body at rest required the application of an outside force. However, it was also believed that it required a continuous outside force to keep a body in motion. Based on their experience with everyday objects, this was not an entirely unreasonable conclusion. After all, if your horse stopped pulling, your wagon would stop rolling, and if the wind stopped blowing, your boat would stop moving.

People therefore assumed that these objects were simply reverting to their natural rest state. It took a remarkable leap of intuition to realize that there had to be an outside force acting to stop the motions of these objects. Take the case of a flat stone sliding on the smooth surface of a frozen lake.

If that stone were a piece of polished marble, it would slide considerably farther than a rough paving stone. Extrapolating to a frictionless surface and ignoring air resistance, we can imagine the object sliding in a straight line indefinitely.

The object would not slow down if friction were eliminated. Consider an air hockey table Figure. When the air is turned off, the puck slides only a short distance before friction slows it to a stop. However, when the air is turned on, it creates a nearly frictionless surface, and the puck glides long distances without slowing down.

Additionally, if we know enough about the friction, we can accurately predict how quickly the object slows down. When the air is off, friction quickly slows the puck; but when the air is on, it minimizes contact between the puck and the hockey table, and the puck glides far down the table. Experiments have verified that any change in velocity speed or direction must be caused by an external force.

The idea of generally applicable or universal laws is important—it is a basic feature of all laws of physics. Identifying these laws is like recognizing patterns in nature from which further patterns can be discovered. Regardless of the scale of an object, whether a molecule or a subatomic particle, two properties remain valid and thus of interest to physics: gravitation and inertia.

Both are connected to mass. Roughly speaking, mass is a measure of the amount of matter in something. Gravitation is the attraction of one mass to another, such as the attraction between yourself and Earth that holds your feet to the floor. The magnitude of this attraction is your weight, and it is a force. Mass is also related to inertia , the ability of an object to resist changes in its motion—in other words, to resist acceleration.

As we know from experience, some objects have more inertia than others. It is more difficult to change the motion of a large boulder than that of a basketball, for example, because the boulder has more mass than the basketball. In other words, the inertia of an object is measured by its mass. The relationship between mass and weight is explored later in this chapter. 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. Thus, unless indicated otherwise, we consider reference frames fixed on Earth to be inertial.