Materials: 10 cans and plaster.

Building Instructions: Fill the Jupiter can with plaster. Since Jupiter has the largest force of gravity we will use that as the planet to compare to and set that equal to 1 (for a plaster filled can). The other planets then become filled in the following amounts:

Mercury .150              Jupiter 1.00

Venus .359                 Saturn .420

Earth .395                  Uranus .364

Moon .063                 Neptune .466

Mars .150                  Pluto .019

By multiplying the weight of the full can by these decimals we can determine how much to fill each can. Unfortunately, Pluto should actually be a little lighter than the weight of a can. Compare each can to get an idea how weight varies on other worlds.

Function and Use: These cans simulate the weight differences on other planets and the Moon. The pull of gravity on an object is known as the weight of the object and pulls on objects towards the center of the planet. The force of gravity depends on the mass of the planet and the radius of the planet as follows:

Forcegravity = Massplanet x Massobject
                       Radiusplanet²

If the mass of an object is twice as big, the weight is twice as big but if the radius of the planet is twice as big, the weight is two squared or four times smaller!