The Bridge V Learning Edition 1 ; our solar system | Page 41

Calculate how much children would weigh on other planets.
Keywords
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Gravity
Mass
Weigh
Planets
Materials
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Paper
Pen
Learning Objectives
Learn about the influence of gravity on the weight of objects on different planets.
Background Science
An astronaut carried out a very special experiment during a moon landing more than 40 years
ago. He held a feather in one hand and a hammer in the other, and then released both objects
simultaneously. Which one reached the ground first? They both hit the floor at the same time! If
there’s no atmosphere, the feather doesn’t experience any air friction, just like the hammer would
barely feel any on earth. In a vacuum, all objects fall at the same speed, regardless of their
mass.
When astronauts landed on the Moon, they had a lot of fun jumping on the lunar surface. Due to
the weak gravitation, they could effortlessly jump very far and high. They felt extremely light.
How much an object weighs on another celestial body depends on the so-called gravity
acceleration. The higher this value, the stronger the celestial body attracts this object, i.e., the
more it weighs. Note that the ‘mass’ of an object is always the same anywhere in the universe.
One kilogram of sugar remains one kilogram of sugar. It just appears as if it had less mass on
the Moon, because it weighs less there. The Moon attracts one kilogram of sugar with less force
than the Earth does.
To see how much one kilogram of sugar and a child of 30 kilograms weigh on the surface of
each planet, see the table below.
Celestial body
Sun
Mercury
Venus
Gravity
acceleration at
the equator
[m/s2]
273.7
3.7
8.87
Multiplier Example 1 kg
sugar [apparent
kg] Example 30 kg
child
[apparent kg]
27.9
0.38
0.9 27.9
0.38
0.9 837
11.4
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