What You Need:



For Experiment 1:

-Empty Jam Jar

-Rice

-Pencil

Experiment 2:

-Balloon or comb

-Faucet

Experiment 3:

-Tennisball

-Basketball

What You Do:



Experiment 1:

Sticky Rice: Get a clean jam jar. Fill to the top with rice. Hold the jar firmly with one hand, push a pencil right to the bottom. Pull the pencil up slowly but not all the way out. Then push it back down again. If the rice level starts to drop, top off the rice. Eventually, the rice will compact around your pencil, and you will be able to lift the whole jar with the pencil. When this happens, the friction between the pencil and rice is so great that you cannot easily pull the pencil out!

The Science:



Every time you plunge the pencil into the rice, you are compressing the grains and making them pack more tightly together. The air gaps decrease in size and the rice grains rub against each other more. They can't move as freely and start to arrange in a pattern that doesn't change. The rice you could previously pour like a liquid becomes solid.

With more grains of rice pressing onto the pencil, and each one of those more tightly packed in, the friction between the pencil and the rice increases. If the friction force between the rice and pencil equals the combined weight force of the rice and the container, then the balance of forces means the pencil is held in place. For the jar to lift as well, friction between its inside walls and the rice must also increase. This proves that the rice has moved and compacted, even where it wasn't disturbed it with the pencil.



Experiment 2:

Bend water with static electricity: Blow up a balloon or use a comb and rub it against your head to build up a static charge. Do this for several minutes to really get a decent charge. Then, turn a tap on: it should be on enough for a steady but slow stream of water to come out, not just drips. Bring the balloon close to the stream of water and observe what happens!

The Science:

When two objects are rubbed against each other, some of the electrons from one object jump to the other. The object that gains electrons becomes more negatively charged; the one that loses electrons becomes more positively charged. The opposite charges attract each other where you can actually see it.

Experiment 3:

Super bouncing: Do this outdoors with a lot of space. Grab a tennis ball. Drop it on the ground and see how high it bounces. Now grab a basketball. Drop it on the ground and see how high it bounces. Now put the tennis ball on top of the basketball; support the basketball with one hand and the tennis ball with the other. Drop your two balls at exactly the same time.

The Science:

When you drop the two balls together, they will separate just a little bit. The basketball will hit the ground first, and will rebound. As it is on the way up, it hits the tennis ball, which is still on its way down. So you have a head-on collision, between balls of very different masses. When this happens, a lot of the energy of the basketball gets transferred to the tennis ball, so watch out as the tennis will end up bouncing very high.