Task: Make a toy or device that converts energy
- Falling & Sliding Cars
Babies do not know how energy is converted, so they are easily interested in toys that convert energies such as cars, speakers, and lights. This toy convert’s the cars’ gravitational potential energies into kinetic energies. As the cars are released at the top, the cars slide down the slope because of the gravitational energies. By repeating this process, the cars reach the bottom. The cars are capable of moving on both sides, so they can still move when they are flipped.
Not all gravitational energy is converted into kinetic energy. The cars create frictions with the slope. Air resistance also takes energy.
Materials:
The cars are made of wooden bodies and wooden wheels. The slides and columns are also made of wood.
Pros: The toy explicitly shows how gravitational potential energy is converted into kinetic energy and is entertaining. It is also relatively easy to manufacture as it does not use complicated parts.
Cons: The car must have small amount of a friction. Since it is a baby toy, materials should not be harmful to health.

2. Pull Back Car
Pull back cars enable a car to move by itself without having people pushing the car directly. Pull back cars convert energy. When a person pulls a car, the spring attached to the wheel of the car is compressed. As the person releases the car, the potential energy of the compressed spring is converted into kinetic energy and delivers energy to the tires through gears. The compressed spring’s potential energy is also converted into various types of energies such as sound, air resistance, and friction between the car and the floor.
Pros: Demonstrates how a compressed spring’s potential energy is converted into kinetic energy. It entertains people by moving by itself.
Cons: Gears and springs are very complicated. They might break easily.

- Motorboat
Motorboat is a boat that moves by the power of a motor. It does not need manpower to make it move. The battery and motor are attached inside of the boat. As the switch is turned on, the electrical energy contained in the battery causes the electrons to flow into the motor, and the electrical energy is converted into kinetic energy. The spinning screw attached to the motor will cause friction with the water so the boat can move forward. However, not the entire electrical energy is converted into the boat’s kinetic energy. Electrical energy is also converted into sound energy and heat energy.
Materials needed: a screw, a battery, a dc motor, a switch, any material that can float on water
Pros: Demonstrates how electric energy is converted into kinetic energy. The toy is also entertaining to play with.
Cons: First of all, the boat must float. It will be challenging to make it floatable. To make it safe, the water must not contact the motor or the battery. The boat cannot steer. It can only go forward. Also, the toy can only be used in water.

https://www.youtube.com/watch?v=ab1da7gk_i8
- Fidget spinner generator
People waste their energy by spinning fidget spinners. However, if a fidget spinner can generate electricity, people can waste less of their energy. The fidget spinner generator generates electricity. If a person spins the spinner, electromagnetic induction occurs, which generates electricity in the coil. A lightbulb will be attached to the coil to confirm that electricity is produced. A person’s kinetic energy of hand converts into the fidget spinner’s kinetic energy. The spinner’s kinetic energy converts into electric energy through electromagnetic induction. Some of the energy is wasted because of air resistance and sound energy.
Materials: a fidget spinner, coil of wire, lightbulb, strong magnets
Pros: Opposite to many devices, it creates electricity, not using electricity.
Cons: Since it requires manpower, it is hard to generate electricity constantly. Also, it won’t spin long as its kinetic energy is converted.

https://www.youtube.com/watch?v=iIFP7K6G9Oo
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