Does gravity only exist on Earth? Nope! Gravity is actually “the force of attraction between any two masses,” so it doesn’t just exist on Earth, and gravity doesn’t just exist between the Earth and other objects. Anything with mass has a gravitational pull. Mass stays the same wherever you go, but gravity is what gives you weight. The more mass an object has, the stronger the gravitational pull, the higher the weight. In the object below, you can see that the astronaut’s mass stays at 120kg whether he’s on Earth or the moon, but his weight changes due to the differences in gravitational pull.
The law of gravitational force looks like this:
(G * m1 * m2) / d^2
G = Gravitational constant
m1 = First object
m2 = Second object
d = Distance between the centers of gravity of m1 and m2
Check out more about gravity here: http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question30.html
Here’s a great video explanation of what gravity is and what it does:
Can we ever defy the force of gravity? Think of a time when you should have fallen but didn't. Think of a roller coaster. People spin upside down without falling out. How is this possible? Can you think of any other examples?
Now that you know what gravity is and does, let’s try a few activities that demonstrate gravity and ways that we can defy it!
Magic paper clips
One way that we can defy gravity is through magnetism. In this experiment, you will see how objects that normally should fall the ground defy the laws of gravity.
YOU WILL NEED:
* Two rulers
* Three strong magnets
* Three paper clips
* Two glasses
Here’s a video preview of what you will be doing:
1. Pick a paper clip up. What happens when you drop it? It falls to the floor.
2. Cut three pieces of string. Each should be the same length, about 6 inches.
3. Tie a piece of string to each paper clip.
4. Tie the other end of each string to a ruler. Make sure they are evenly spaced apart. What happens when you pick the ruler up? The paper clips should dangle below. If you tilt the ruler, what do the paper clips do? Notice that they all continue to point directly at the ground, no matter which way you tilt the ruler.
5. Tape three magnets to your second ruler. They should be equally spaced out and should align with the paper clips on your first ruler. For example, if you tied your paper clips at 2inches, 6inches, and 10inches on the first ruler, that’s where you should tape your magnets on the second ruler.
6. Set a glass (at least 7 inches tall) on each side of the first ruler.
7. Place the ruler with the magnets across the glasses with the magnets facing down.
8. Lift each paper clip towards the magnet. What happens? You should see all three paper clips floating in mid-air! Why is this happening? The magnets are attracting the metal paper clips, causing them to defy gravity!
9. Lift the ruler with the magnets. What happens to the paper clips? Without the magnetism pulling on them, they comply with the laws of gravity and crash back to the ground.
In this experiment, you’ll see another way that we can defy gravity!
YOU WILL NEED:
* Piece of cardboard
Here’s what to do!
1. Pour water into the glass all the way to the top. Make sure it’s right up to the rim.
2. Cut a square of cardboard big enough to cover the mouth of the glass.
3. Carefully place the cardboard over the mouth of the glass. Make sure there are no space for air or air bubbles in the glass!
4. Carry the glass to the sink with your hand over the cardboard. Flip the glass upside-down.
5. Remove your hand from the cardboard. What happens? The cardboard stays in place, keeping the water from falling out! Defying gravity!
6. Why does this happen? The air pressure outside the glass is greater than the pressure of the water inside the glass, so the cardboard stays in place.