# Measuring Inertial Mass: Force, Acceleration and Mass

• Swapnil
In summary, Scientists measure inertial mass by comparing it with a known standard mass, either directly using a balance or indirectly using a calibrated device. This known mass is compared with another standard mass, and the chain continues until it reaches a chunk of platinum-iridium alloy in Paris, which is by definition one kilogram. The concept of forces is used in the measurement of mass, but the only requirement is that two objects with the same mass be affected equally by equal forces. The mass is a fundamental SI measurement and is defined by the kilogram in Paris.
Swapnil
I was wondering, how is it that scientists measure inertial mass. I presume they use F=ma, and thus the mass of an object would be measured by applying a force on an object and finding out the resulting acceleration. Getting acceleration is simple, but how can they measure the force? Then if they can't measure the force, then how can they measure the mass?

Normally one measures the mass of an object by comparing it with a known standard mass, either directly using a balance, or indirectly by using a device (like a spring) that is calibrated using known masses.

One finds the mass of the "known" mass by comparing it with yet another standard mass, etc. The end of the chain is a chunk of platinum-iridium alloy stored under controlled conditions in a basement in Paris, whose mass is by definition exactly one kilogram.

jtbell said:
Normally one measures the mass of an object by comparing it with a known standard mass, either directly using a balance, or indirectly by using a device (like a spring) that is calibrated using known masses.
But doesn't a balance or a spring use the concept of forces to give you the measured mass? And forces are actually dependent on mass... I don't know why, but doesn't all of this seem to be circular?

Swapnil said:
But doesn't a balance or a spring use the concept of forces to give you the measured mass?

The only requirement is that two objects with the same mass be affected equally by equal forces.

mass is a si measurement therefore you can think of it as the beggining...like jtbell said it is defined in paris by a piece of metal which is defined to be 1Kg

## 1. What is inertial mass?

Inertial mass is a measure of an object's resistance to changes in its state of motion. It is a property of matter that determines how much force is needed to accelerate an object.

## 2. How is inertial mass measured?

Inertial mass is typically measured by comparing the acceleration of an object to the applied force. This can be done using a variety of instruments, such as a balance scale or an accelerometer.

## 3. What is the relationship between force, acceleration, and mass?

According to Newton's Second Law of Motion, the force applied to an object is directly proportional to its mass and acceleration. This can be represented by the equation F = ma, where F is force, m is mass, and a is acceleration.

## 4. How does mass affect an object's inertia?

The greater an object's mass, the greater its inertia. This means that a larger force is needed to accelerate an object with a higher mass compared to one with a lower mass.

## 5. Can the inertial mass of an object change?

The inertial mass of an object remains constant, regardless of its location or the force applied to it. This is known as the principle of conservation of mass. However, the mass of an object can change if matter is added or removed from it.

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