Day 2

Light, Sound & Bubble Energy

MAKING A PERISCOPE ~ SUPER SOUND CONE ~ BUBBLE-POWERED ROCKET

Up Periscope!

A periscope is an optical instrument that uses a system of prisms, lenses, or mirrors to reflect images through a tube. Light from a distant object strikes the top mirror and is then reflected at a 90 degree angle down the periscope tube. At the bottom of the periscope, the light strikes another mirror and is then reflected to the viewer's eye. Both mirrors in this instance are held in place at 45 degree angles.

This simple periscope uses only flat mirrors as compared to the periscopes used on submarines, which are usually a complex optical system using both lenses and mirrors.

The first known periscope was designed and constructed by Johannes Gutenberg sometime in the 1430s. His inspiration to invent such a device was to allow people an advantage in seeing over crowds of other people at festivals. In 1647, an astronomer by the name of Johannes Hevelius designed and built a periscope using lenses for military use.

ACTIVITY: Creating a Periscope

MATERIALS NEEDED:

2 flat mirrors

Cardboard tube with openings at the end - milk or juice cartons will work (see the picture example)

Craft sticks for support

Tape

Ruler

Scissors

Purpose of this Experiment:

You will be able to experiment and see that images or light reflected in a mirror are reversed or reflected depending on how parallel the mirrors are held.

Can you hear me now?

Like the waves in the ocean, sound makes waves in the air. Air moves back and forth as the energy of the sound waves pass.

If you put something like paper in the path of sound waves, it will vibrate. This is fun to try out. One thing that is fun to do is to place a piece of paper on top of a speaker and then adjust the volume of the speaker to see what happens to the paper. If you can lay your speaker down horizontally and place the paper on top of it, try sprinkling just a little cocoa powder on top and seeing if you can see patterns created depending on what is being transmitted through your speaker.

If you give this paper the right shape, the sound waves will funnel to a point making the sound cone you are going to build...now it's a sound funnel! This is the same idea that makes NASA's giant dish antennas work. These antennas listen for signals from planetary space craft that are exploring space far from Earth.

We can't just build a spacecraft and tell it to "phone home" after launching it! We have to have a way to hear "its voice" (or signal) and "talk to it" (send it messages) from very far away. Of course no spacecraft actually communicates by sound because sound waves cannot travel through the vacuum of space. There is no air present for the sound waves to travel! Instead, the spacecraft send radio waves that can travel practically forever. The problem though is that radio waves spread out and get weaker as they travel. So NASA's radio wave "ears" have to be very big.

While these dis antennae do not look like sound cones, the path the radio signals take once they hit the dish is similar to the sound cone you are about to make. Once the signal hits - like the small end of your cone, electronic instruments then take over to turn up the volume!

ACTIVITY: Super Sound Cone

MATERIALS NEEDED:

A paper plate or poster board to make the cone

Tape

The Event Horizon Telescope

In March of 2019, the first image ever compiled showing the existence of a black hole was shared by the Event Horizon Telescope. This "telescope" is made up of eight satellite dishes placed in in strategic locations all over the world.

Pop, pop, fizz, fizz...

Real rockets work kind of the same way as the bubble rocket. But, instead of using tablets that fizz in water, they use rocket fuel.

The rocket that launched Deep Space 1 on October 24, 1998, had four different types of engines:

Some pushed the rocket off the ground.
Some helped it to continue its climb into space.
Others gave the final push into space and away from Earth.

But, all of the engines forced gas to shoot out of the rocket, pushing the rocket in the opposite direction, much like you are going to do in the "Bubble Powered Rocket" activity.

ACTIVITY: Bubble-Powered Rocket

MATERIALS NEEDED:

Plastic film canister (or similar container)

Tape

Scissors

Effervescing Antacid Tablet

Paper towels

Template for rocket (optional)

Water (...not optional)

How does this work?

When the fizzy, effervescing tablet, is placed in the water, many little bubbles of gas escape. The bubbles go up, instead of down, because they weigh less than water. When the bubbles get to the surface of the water, they break open and release the gas inside. All escaped gas from the bubbles pushes on the sides of the canister. Think about when you blow up a balloon, the air makes the balloon stretch bigger and bigger. But, the film canister does not stretch and all the gas has to go somewhere!! Eventually, something has to give. So the canister pops its top or bottom because it is upside down. All the water and gas rush down and out, pushing the canister up along with the rocket attached to it. This is an example of Newton's 3rd Law of Motion: "For every action, there is an equal and opposite reaction." The first action is the gas rushing out of the canister as the top comes off. The reaction is the canister being pushed up in the opposite direction of the escaping gas. In a similar way with a real rocket, the rocket goes in the opposite direction of the gas being propelled out from its engines. The faster the gas leaves the rocket, the faster the rocket is pushed the other way.

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