What do newtons laws of motion mean

If we were discussing the flight of a baseball , then certainly the mass remains a constant. But if we were discussing the flight of a bottle rocket , then the mass does not remain a constant and we can only look at changes in momentum. The change in velocity divided by the change in time is the definition of the acceleration a. The second law then reduces to the more familiar product of a mass and an acceleration:. Remember that this relation is only good for objects that have a constant mass.

This equation tells us that an object subjected to an external force will accelerate and that the amount of the acceleration is proportional to the size of the force. The amount of acceleration is also inversely proportional to the mass of the object; for equal forces, a heavier object will experience less acceleration than a lighter object. 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. It takes some force acting on them from the outside to cause such a change. This property of massive bodies to resist changes in their state of motion is sometimes called inertia. The Second Law of Motion describes what happens to a massive body when it is acted upon by an external force.

It states, "The force acting on an object is equal to the mass of that object times its acceleration. The bold letters indicate that force and acceleration are vector quantities, which means they have both magnitude and direction.

The force can be a single force, or it can be the vector sum of more than one force, which is the net force after all the forces are combined. When a constant force acts on a massive body, it causes it to accelerate, i. In the simplest case, a force applied to an object at rest causes it to accelerate in the direction of the force. He defined any change in speed and direction as acceleration and therefore argued that orbital motion is a kind of acceleration.

This is a transcript from the video series The Joy of Science. Watch it now, on Wondrium. While speeding up is referred to as positive acceleration, an action of slowing down, such as applying the brakes of a car, is negative acceleration. Mathematically, acceleration is expressed using the concept of the vector.

In a mathematical vector, both direction and speed are defined. It can be represented as an arrow, where the arrow denotes the direction, and the length corresponds to the speed. Learn more about the nature of energy.

Every body continues in its state of rest or of uniform motion in a [straight] line unless it is compelled to change that state by forces impressed upon it.

This means an object will not change its motion unless acted upon by an external force. This law conveys three distinct types of behavior by objects. The first one being that an object moves at a constant speed in the same direction as it goes along.

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. Using duct tape, attach two tennis balls to opposite ends of the coat hanger as shown in the diagram at the right.

Bend the hanger so that there is a flat part that balances on the head of a person. The ends of the hanger with the tennis balls should hang low below the balancing point.

Place the hanger on your head and balance it. Then quickly spin in a circle. What do the tennis balls do? Physics Tutorial. My Cart Subscription Selection. Student Extras.