Gravity for Elementary and Middle students (Teach)
Gravity: the phenomenon that keeps our feet on the ground:By Moira Whitehouse PhD
Gravity is a force.Gravity is a force that pulls.Every object has gravity.So every object pulls on every otherobject.The more mass an object has, the harderit pulls.
We will use two hypothetical planets for ourexample. Both the blue and green planetsare pulling on each other. Which one pulls harder?
This should help us see that the more mass an object has the stronger its gravity. Moon Earth The Earth obviously has more mass thanBut the Moon’s gravity is also pulling on the Moon and it pulls harder.the Earth. So hard that the oceans swell So much harder that theever it passes. in antoward the Moon where Moon is held Wecall this high tide. Earth as though by some orbit around the magically strong string.
Let’s think about gravity on our favorite littleplanet, Earth.
Gravity on Earth pulls everything towardits center.
That’s why there isno top or bottomand no one fallsoff.
If you dug a holeright through theEarth and fell in,how far wouldyou fall?
You’d fall into the hole and shoot right past the center because you would be going so fast. As soon as you passed it, youwould be pulledback towards thecenter. So youwould bounce backand forth like abungie jumper tillyou finally stoppedat the center.
On Earth it appears that not everything falls to the ground at the same rate.It seems to us that things with lessmass or weight e.g. feathers fallslower than things with more massor weight e.g. rocks. This is a misconception.As demonstrated by Galileo in the 1500’s, allobjects in a vacuum, fall at the same rateregardless of mass.Lighter objects on Earth fall slower due toour atmosphere which slows their descent.
On the Moon, an astronaut dropped afeather and a hammer.Since there is no atmosphere on theMoon the feather and the hammer hitthe ground at the same time.
The weight of an object is a measure ofhow hard gravity pulls on it.However, the amount of gravity on eachplanet differs. The Moon has only one-sixthas much gravity as the earth. Consequently,on the moon you would weigh only one-sixth of what you weigh on Earth.
Since each planet has adifferent amount ofgravity, this boy’sweight would changeeach time he went toanother planet.
On Jupiter,this would belike carryingan extra 100poundsaround onyour back allday.
The farther an object is from the center ofa planet, the weaker the force of gravity.So, would this apple weigh more in someplace like Death Valley or on top of a veryhigh mountain?
Weight of a one pound apple heading outto space. Apple Apple Apple Apple weighs weighs weighs weighs 1 pound 1/4 pound 1/9 pound 1/16 pound here here here here
In a spaceship like the shuttle, you would beweightless. However this is not becauseyou are so far from Earth that there is nogravity. It is because the spaceship, beingpulled by gravity, is always falling frombeneath you.
Both of these men are weightless, still they areboth being pulled by gravity. They have weightonly when gravity pushes them againstsomething like the floor or a scale.
What causes gravity?Even the great At his timeSir Isaac Newton and stillcouldn’t answer today, whatthat one. causes gravity is a mystery.But it is a force that effects everything inthe universe.