Relationship between momentum and inertia | Physics Forums
Momentum vs Inertia Inertia and momentum are two concept involved in the study of motion of solid bodies. Momentum and inertia are used to describe the. The moment of inertia, otherwise known as the angular mass or rotational inertia, of a rigid Moment of inertia also appears in momentum, kinetic energy, and in Newton's laws of motion This relationship is called the parallel axis theorem. Inertia, Momentum, Impulse, and Kinetic Energy. Forces change an object's motion, but without them, an object will keep doing whatever it was doing.
It has no magnitude or measurement units. To quantify Inertia, physicists developed the more specific concept of Momentum, which has quantities of mass, speed, and direction.
Moment of inertia - Wikipedia
Inertia is the observed natural tendency of an object in motion to keep moving in the same direction and at the same speed, or if at rest, to stay at rest. In physics, we quickly learn the the only difference between an object moving or being at rest is the relative motion of the observer, so both of these cases are really the same thing. Inertia simply tells us that to change the motion of an object requires applying a force to it. To fully describe the property of Inertia with units we can measure, we must quantify an object's speed of motion, direction of motion, and resistance to change of motion.
We combine these three things into a single parameter for each object called its Momentum. The resistance to change of motion does not depend upon direction, so it is what we call a "scalar" quantity, and has been named Mass. We quantify Mass using units such as kg or lb-mass.
Inertia, Momentum, Impulse, and Kinetic Energy
Objects that require a lot of Force to accelerate a little bit have large Mass. Objects that accelerate a lot with a little bit of Force have small Mass. Speed is also a scalar quantity, but when we combine speed with direction, we get a "vector" quantity called Velocity.
Momentum has both a magnitude and a direction.
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Velocity, by contrast, is a vector. If one were to say "50 miles per hour toward the northeast," this would be an expression of velocity. Vectors are typically designated in bold, without italics; thus velocity is typically abbreviated v.
How it works - Momentum - Momentum and Inertia, Mass and Weight, Velocity and Speed
Scalars, on the other hand, are rendered in italics. Hence, the formula for momentum is usually shown as m v. Linear Momentum and Its Conservation Momentum itself is sometimes designated as p.Relationship between angular momentum and moment of inertia -- class 11 -- unit 5.
It should be stressed that the form of momentum discussed here is strictly linear, or straight-line, momentum, in contrast to angular momentum, more properly discussed within the framework of rotational motion. Both angular and linear momentum abide by what are known as conservation laws. These are statements concerning quantities that, under certain conditions, remain constant or unchanging.
The conservation of linear momentum law states that when the sum of the external force vectors acting on a physical system is equal to zero, the total linear momentum of the system remains unchanged—or conserved.
The conservation of linear momentum is reflected both in the recoil of a rifle and in the propulsion of a rocket through space. When a rifle is fired, it produces a "kick"—that is, a sharp jolt to the shoulder of the person who has fired it—corresponding to the momentum of the bullet.
Why, then, does the "kick" not knock a person's shoulder off the way a bullet would? Because the rifle's mass is much greater than that of the bullet, meaning that its velocity is much smaller. As for rockets, they do not—contrary to popular belief—move by pushing against a surface, such as a launch pad. If that were the case, then a rocket would have nothing to propel it once it is launched, and certainly there would be no way for a rocket to move through the vacuum of outer space.