I don’t even know really what intertia means let alone moment of it??
Plz help
In: 6
Newton’s first law of motion can be said as:
>An object will not change its motion unless a force acts on it.
When a force acts on an object, it changes its motion. However, the more inertia the object has, the more force you need to change its motion. This is why throwing a basketball does less damage than throwing a bowling ball.
“Moment of inertia” is also known as angular mass. Mass, the regular one, is a factor in how much force you need to make an object move by pushing it. Angular mass (aka moment of inertia) is a factor in how much torque you need to make an object spin by turning it.
I think the reason they call it the “moment” is because it’s how much force is needed in a single moment, but I really don’t know. Science is full of awful naming choices that confuse people.
Newton’s first law of motion can be said as:
>An object will not change its motion unless a force acts on it.
When a force acts on an object, it changes its motion. However, the more inertia the object has, the more force you need to change its motion. This is why throwing a basketball does less damage than throwing a bowling ball.
“Moment of inertia” is also known as angular mass. Mass, the regular one, is a factor in how much force you need to make an object move by pushing it. Angular mass (aka moment of inertia) is a factor in how much torque you need to make an object spin by turning it.
I think the reason they call it the “moment” is because it’s how much force is needed in a single moment, but I really don’t know. Science is full of awful naming choices that confuse people.
Inertia is what makes heavier objects more difficult to get moving or to stop them from moving. For example, if you push on a bowling ball, it takes more effort to get moving than a soccer ball. Inertia is also the reason a bowling ball is more difficult to stop.
When things are moving in a straight line, inertia is simple. Heavier objects have more inertia.
But what about when things are rotating? That’s when things start to get interesting. The “moment of inertia” is what we use to describe inertia for rotating objects.
If you have an office chair nearby, sit down, extend your arms, and have someone spin you around. Careful, not too fast. Once you’re spinning, quickly pull your arms in, wait a moment, then extend them again.
You’ll notice that you rapidly speed up when you draw your arms in, then slow down when you extend them again. What’s up with that!?
The reason is really interesting, but also very simple. When you spin around with your arms extended, the mass in your hands and arms travels a path that is a circle. The linear distance traveled around one revolution is called the circumference. When you draw your arms inwards, that distance becomes shorter, but the mass in your arms has momentum from traveling a greater distance. By reducing the distance your hands will travel, you speed up your rate of rotation.
So the moment of inertia considers the mass of the rotating object, its angular velocity (same as RPM), and the distance of its mass from the center of rotation. All three of these values are “conserved” under the law of conservation of energy. So if you change any one of those variables, the others will adjust to compensate.
Inertia is what makes heavier objects more difficult to get moving or to stop them from moving. For example, if you push on a bowling ball, it takes more effort to get moving than a soccer ball. Inertia is also the reason a bowling ball is more difficult to stop.
When things are moving in a straight line, inertia is simple. Heavier objects have more inertia.
But what about when things are rotating? That’s when things start to get interesting. The “moment of inertia” is what we use to describe inertia for rotating objects.
If you have an office chair nearby, sit down, extend your arms, and have someone spin you around. Careful, not too fast. Once you’re spinning, quickly pull your arms in, wait a moment, then extend them again.
You’ll notice that you rapidly speed up when you draw your arms in, then slow down when you extend them again. What’s up with that!?
The reason is really interesting, but also very simple. When you spin around with your arms extended, the mass in your hands and arms travels a path that is a circle. The linear distance traveled around one revolution is called the circumference. When you draw your arms inwards, that distance becomes shorter, but the mass in your arms has momentum from traveling a greater distance. By reducing the distance your hands will travel, you speed up your rate of rotation.
So the moment of inertia considers the mass of the rotating object, its angular velocity (same as RPM), and the distance of its mass from the center of rotation. All three of these values are “conserved” under the law of conservation of energy. So if you change any one of those variables, the others will adjust to compensate.
So what’s the difference between mass and inertia when an object is simply just moving linearly and not rotating?
So what’s the difference between mass and inertia when an object is simply just moving linearly and not rotating?
Inertia is a measure of how hard it is to get something to change its velocity (that is, to speed up, slow down, or change direction). It’s essentially equivalent to mass – massive objects take more force to speed up, slow down, or to get them to change direction when they’re moving.
Moment of inertia is the same idea, but for rotation. Objects with a high moment of inertia take a lot of torque (the rotational equivalent of force) to speed up their rotation, slow down their rotation, or change the direction they’re rotating. Moment of inertia depends not only on how massive an object is, it also depends on how far away each part of the object is from the axis of rotation. More spread out mass means a higher moment of inertia, and more concentrated mass means a lower moment of inertia.
Moment of inertia is related to angular momentum. The angular momentum of an object is equal to its moment of inertia, multiplied by its angular velocity (like how linear momentum is equal an objects mass multiplied by its velocity). Angular momentum is conserved, which explains some things about the behaviour of spinning objects. The classical example here is an ice skater spinning on the spot, and then drawing their arms in to spin faster. They don’t change their mass, but by moving their arms inwards, they move their mass closer to the axis of rotation, which decreases their moment of inertia. Since angular momentum is conserved, their angular velocity has to increase to compensate, and they spin faster.
Inertia is a measure of how hard it is to get something to change its velocity (that is, to speed up, slow down, or change direction). It’s essentially equivalent to mass – massive objects take more force to speed up, slow down, or to get them to change direction when they’re moving.
Moment of inertia is the same idea, but for rotation. Objects with a high moment of inertia take a lot of torque (the rotational equivalent of force) to speed up their rotation, slow down their rotation, or change the direction they’re rotating. Moment of inertia depends not only on how massive an object is, it also depends on how far away each part of the object is from the axis of rotation. More spread out mass means a higher moment of inertia, and more concentrated mass means a lower moment of inertia.
Moment of inertia is related to angular momentum. The angular momentum of an object is equal to its moment of inertia, multiplied by its angular velocity (like how linear momentum is equal an objects mass multiplied by its velocity). Angular momentum is conserved, which explains some things about the behaviour of spinning objects. The classical example here is an ice skater spinning on the spot, and then drawing their arms in to spin faster. They don’t change their mass, but by moving their arms inwards, they move their mass closer to the axis of rotation, which decreases their moment of inertia. Since angular momentum is conserved, their angular velocity has to increase to compensate, and they spin faster.
You’ve probably heard Newton’s first law of motion, that absent any outside force, an object in motion tends to stay in motion and an object at rest tends to stay at rest. This is the principle of inertia. It means that a force is required to change an object’s velocity.
Inertia is affected by the object’s mass. The classic formula F = ma, force equals mass times acceleration, can be written as a = F/m, acceleration equals force divided by mass. So the more mass something has, the less it will accelerate when a force is applied.
A “moment” in physics means the product of a physical quantity and a distance, but usually when we use the word “moment” we are specifically talking about torque: a product of force and distance. Torque (or moment) is the rotational equivalent of force; you apply it to cause an object to rotate; to change rotational velocity.
The moment of inertia is the rotational equivalent to mass. It tells you how much the object will resist rotational acceleration (usually called angular acceleration) for a given torque. So we can take the a = F/m formula and come up with its rotational analog. α is angular acceleration, 𝜏 is torque, and I is moment of inertia. So the formula becomes α = 𝜏/I. The angular acceleration equals torque divided by moment of inertia.
You’ve probably heard Newton’s first law of motion, that absent any outside force, an object in motion tends to stay in motion and an object at rest tends to stay at rest. This is the principle of inertia. It means that a force is required to change an object’s velocity.
Inertia is affected by the object’s mass. The classic formula F = ma, force equals mass times acceleration, can be written as a = F/m, acceleration equals force divided by mass. So the more mass something has, the less it will accelerate when a force is applied.
A “moment” in physics means the product of a physical quantity and a distance, but usually when we use the word “moment” we are specifically talking about torque: a product of force and distance. Torque (or moment) is the rotational equivalent of force; you apply it to cause an object to rotate; to change rotational velocity.
The moment of inertia is the rotational equivalent to mass. It tells you how much the object will resist rotational acceleration (usually called angular acceleration) for a given torque. So we can take the a = F/m formula and come up with its rotational analog. α is angular acceleration, 𝜏 is torque, and I is moment of inertia. So the formula becomes α = 𝜏/I. The angular acceleration equals torque divided by moment of inertia.
Latest Answers