Kilogram (kg) is a unit of mass.
Understanding Mass vs. Weight
It's crucial to understand the distinction between mass and weight.
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Mass: Mass is a fundamental property of an object that measures its resistance to acceleration. It's a measure of the amount of matter in an object and remains constant regardless of location. The kilogram (kg) is the standard unit for mass in the metric system.
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Weight: Weight, on the other hand, is the force exerted on an object due to gravity. Weight depends on both the object's mass and the gravitational acceleration at its location. The unit of weight is the Newton (N). Weight = mass * gravitational acceleration (W = mg).
Kilogram as a Unit of Mass
The kilogram (kg) is defined as the unit of mass. Originally, it was intended to be the mass of 1,000 cubic centimeters (1 liter) of water. While the definition has evolved, the kilogram remains the standard unit for quantifying mass. Therefore, when you measure something in kilograms, you are measuring its mass, not its weight. To determine the weight, you would need to factor in the local gravitational acceleration.
Example
Consider an object with a mass of 1 kg:
- On Earth (gravitational acceleration ≈ 9.81 m/s²), its weight would be approximately 9.81 N.
- On the Moon (gravitational acceleration ≈ 1.625 m/s²), its weight would be approximately 1.625 N.
The mass remains 1 kg in both locations, but the weight changes due to the varying gravitational forces.
