WEIGHT AND MASS
"How much do you weigh in kilograms Bob?" said Sue. "Mind your own business Sue!" says Bob, "And anyway, get your physics right Sue, I can't "weigh" myself in kilograms anyway! That's a measurement of my mass and nothing to do with "weight", which is indeed a force caused by gravity and varies, depending on which planetary body I am standing on, due to it's gravitational field strength......er... Sue? .....Sue...sue...come back? Well, charming, she's left...... Sue?"
How many times have we all had such conversations? Hardly ever. But it it vitally important in physics and engineering to know the difference between mass and weight. Watch this video to find out, where we actually launch some of our lovely science geeks into space to investigate and find out more.......Also - Check out our QUIZ at the bottom of the page!
MASS AND WEIGHT: THE KEY FACTS
The key differences between mass and weight are:
Mass:
It is a measure of the amount of matter in an object.
Mass is a scalar quantity, which means it only has magnitude and no direction.
It is measured in units like kilograms or grams.
Mass is constant and does not change regardless of location, even when an object is on the Moon or Earth.
Weight:
It is a measure of the force of gravity acting on an object’s mass.
Weight is a vector quantity, which means it has both magnitude and direction (towards the center of the gravitational source).
It is measured in units like newtons or pounds.
Weight can change with the location of the object because it depends on the gravitational pull, which varies from one celestial body to another.
Weight ( W ) can be calculated using the formula:
where:
( m ) is the mass of the object,
( g ) is the acceleration due to gravity.
So, if you were to take a 1-kilogram mass to the Moon, its mass would remain 1 kilogram, but its weight would be less because the Moon’s gravitational pull is weaker than the Earth’s.
