Bet you can't!
Want to play around with gravity?
Here are some fun tricks you can try out on your friends and family.
The Impossible Leap:
- While standing up, bend over and hold your toes with your hands, keeping your knees slightly bent.
- Try to jump forward in this position without removing your hands from your toes while you are jumping.
- Can you do it? Bet you can't!
The Science:
In this position, you can jump backwards from one end of the room to the other, but you won't be able to jump forward even a single step! When we jump, we first shift our center of gravity in the direction we want to jump, and then we move our support base in the same direction to regain our balance. When you are holding onto your toes, jumping backwards is not a problem because you can use your heels. But to jump forward, you would have to use your toes... and your fingers are in the way.
___
The Super Glue Chair:
- Sit in a straight-back armless chair, keeping your back against the back of the chair and your feet flat on the floor.
- Fold your arms across your chest.
- Keeping your feet flat and your back straight, try to stand up.
- Are you glued to your chair?
The Science:
In this sitting position, the center of gravity is at the base of your spine. By trying to stand up with your back straight, you prevent the center of gravity from moving to a position above your feet, which would be necessary to stand up. Therefore, you remain glued to your chair!
___
Pick Up Trick:
- Place an object on the floor about 20 inches from a wall.
- Stand with your back against the wall, feet together, and heels against the wall.
- Try to pick up the object on the floor without moving your feet or bending your knees.
- Can you do it? Bet you can't!
The Science:
There is no way you can pick up that object. When you stand straight against the wall, your center of gravity is over your feet. When you bend forward, you move your center of gravity forward. In order to keep your balance, you must move your feet forward, too. This makes sure that the center of gravity is right above your feet to maintain stability. Since the rules of this trick do not allow you to move your feet, there is no way you can make the balance shift so that the center of gravity is maintained over your feet. That is why you are unable to pick up the object. And, if you insist on picking up the object, you will fall flat on your face!
___
Leg Lift:
- Stand against a wall with your right side facing the wall, then put your right foot and cheek against the wall.
- Try to lift your left foot off the floor.
- Can you do it? Bet you can't!
The Science:
You will not be able to lift your foot off the ground at all! This trick requires you to shift your center of gravity over your right foot. You cannot do this without moving the wall. In our everyday life, our body maintains balance with the little adjustments that are so automatic that we never think about them.
___
Notes About Gravity:
Gravity is the force of attraction between bodies or objects that have mass. Gravity exerts its force in such a way that all the weight of a body seems to be concentrated at a single point. If a body has a supporting base, its center of gravity must be located directly over the base or the body will tip cover. An object with a regular shape, such as the Earth, has a center of gravity, which is very easy to locate - at the geometric center. But irregular shaped objects, like the human body, do not necessarily have a center of gravity that coincides with the geometric center. In fact, for human beings, the center of gravity can be at different spots when we are doing different activities. For example, when we are skiing or doing gymnastics, our center of gravity is always shifting from one part of our body to another.
