This is intended as an end-of-year activity. When kids are finished making frogs, we do a summary of all activities learned throughout the year–a bit of a question-answering contest.
Soap film must stretch to include the air trapped inside it, or reach the surfaces that form its boundaries. The more soap film stretches, the more elastic potential energy it gains. Soap film will stretch as little as possible to keep its potential energy low. The soap film will try to keep its surface area small.
When light travels from one material to another it usually changes speed. This change in speed makes light bend, and our eyes can see the change.
The refractive index is a measure of the change in speed of light when it passes from one material (like water or air) into another.
This activity uses two objects that have a similar refractive index, and light does not get bent (refracted) when it passes through the baby oil and into the glass. As no light is bent, our eyes cannot see a change in what’s there.
Reflection occurs when light bounces off objects. How much reflection depends upon how even the surface is. If the surface is rough, the light scatters. If the surface is smooth and flat, the light will bounce off it at equal angles. That is why a flat mirror reflects a good likeness of the object being reflected.
The solar energy will heat up the air inside the bag causing the molecules to move around and bump into all sides of the solar bag and make it rise! This is a perfect experiment to learn about the properties of air, buoyancy and convection. It’s amazing science at work!
For the bouncing ball:
– 1 person holds the yard stick against the wall
– 1 person holds the ball at a short height and bounces the ball
– 1 person keeps track of how high the ball goes
– repeat for multiple heights
For the car:
– open their lab notebook slightly to make a small ramp.. roll the car down and measure how far it goes
– keep making the ramp steeper.. measure how far the car goes
For the poppers:
– each person takes turns doing the popper once
– discuss.. what gives the popper potential energy? Where was work done on the popper?
An object can store energy as the result of its position. For example, the heavy heavy ball of a demolition machine is storing energy when it is held at an elevated position. This stored energy of position is referred to as potential energy. Similarly, a drawn bow is able to store energy as the result of its position. When assuming its usual position (i.e., when not drawn), there is no energy stored in the bow. Yet when its position is altered from its usual equilibrium position, the bow is able to store energy by virtue of its position. This stored energy of position is referred to as potential energy. Potential energy is the stored energy of position possessed by an object.
If you lift an object up, you put energy into the gravitational field. This energy is not immediately apparent. It is stored energy. The higher you lift the object, the more the energy is stored in the gravitational field. So, the amount of energy that is stored is a function of where you locate the object, a function of how high up you lift it. Therefore, potential energy is not only called stored energy, it is also called energy dependent upon position
When water is added to the Alka-Seltzer tablet, bubbles of carbon dioxide gas are given off. When the lid is fitted tightly to the canister this gas is contained within an enclosed space. As more gas is given off the pressure inside the canister rises until there is enough force to overcome the seal of the lid. The built up pressure exerts enough force to shoot the canister into the air, forming the rocket.
Make sure the film canister lid is tightly fitting or you will only get a disappointing ‘fizz’. You should also clean the canister lip and lid between demonstrations so that no pieces of Alka-Seltzer get stuck between them, ruining the seal.
Applying pressure to the mixture increases its viscosity (thickness). A quick tap on the surface of Oobleck will make it feel hard, because it forces the cornstarch particles together. But dip your hand slowly into the mix, and see what happens—your fingers slide in as easily as through water. Moving slowly gives the cornstarch particles time to move out of the way.
Oobleck and other pressure-dependent substances (such as Silly Putty and quicksand) are not liquids such as water or oil. They are known as non-Newtonian fluids. This substance’s funny name comes from a Dr. Seuss book called Bartholomew and the Oobleck.
Dry ice is carbon dioxide (CO2) in its solid form. At temperatures above -56.4 °C (-69.5 °F), dry ice changes directly from a solid to a gas, without ever being a liquid. This process is called sublimation. When dry ice is put in water it accelerates the sublimation process, creating clouds of fog that fill up your dry ice bubble until the pressure becomes too much and the bubble explodes, spilling fog over the edge of the bowl. Dry ice is sometimes used as part of theater productions and performances to create a dense foggy effect. It is also used to preserve food, freeze lab samples and even to make ice cream!