Create the quickest rubber band paddle boat

Paddle boat (Figure 1) was very common in the 1800s. They were usually equipped with steam engines. Most modern boats use propellers instead of paddles, but there are still small human paddle boats with bike-like pedals (Figure 2) and smaller angular paddle boats (Figure 3) that can be used as bathtub or pool toys.

The paddle boat in Figure 3 is equipped with a rubber band. Roll up the rubber band and store it Potential energy. When you release a rubber band, the paddle will spin, push water, force. When the paddle pushes the water, the water is pushed back into the paddle, pushing the boat forward (this is called Newton’s Third Lawor “There are equally opposite reactions for all actions.”). The potential energy stored in rubber bands is Kinetic energythe energy of movement as the boat moves forward.

Other forces also act on the paddle boat as they advance. Paddle boat itself Weight I’ll lower that, but Buoyancy Float it from the water. Friction from the water passing the boat, or dragslow the boat.

To make the boat as fast as possible, you need the largest push and minimum drag from the paddle. There are many ways to change these forces. For example, the shape of the paddle or Hull (Body) of a boat. You can also try making your boat from a variety of materials. This project uses an engineering design process to design, test and improve the boat. How fast does your boat go?

Terminology and concepts

• Paddle boat
• Potential energy
• force
• Newton’s Third Law
• Kinetic energy
• Weight
• Buoyancy
• drag
• Hull

question

• What materials do you think can be used to build a paddle boat?
• What forces work on a moving paddle boat?
• How do you think you can change the shape of your paddle boat to make it faster?

resource

Materials and equipment

• Rubber band
• Boat ingredients like:
  • Cardboard (Duty tape is required to waterproof)
  • Balsa Wood
  • Popsicle stick (Hot glue gun is required for assembly)
• Optional: Small fragments of bubbles to make your boat better
• pencil
• ruler
• Hobby knife or scissors
• Bathtub or Kiddy Pool
• Stopwatch or tape measure

Experimental procedure

1. Fill the bathtub or children’s pool with water so that the boat is ready to test.
2. There are three different basic boat designs that can be constructed depending on the materials available. Three videos show a boat made from balsa wood, cardboard and popsicle sticks. Try starting by building one of these boats. However, you can also combine the materials (for example, use a mix of balsa wood and popsicle sticks).
3. Test the boat with water. Write down your observations about the boat and the issues you notice. for example:
   1. How far will you go until it stops? If the boat doesn’t make it completely beyond the pool/tub, you can measure this with a tape measure.
   2. How long does it take if you are going all the way past the pool/bathtub? This can be measured with a stopwatch.
   3. Does the boat go straight?
   4. Does the boat seem to be struggling underwater or will it sink?
4. Based on your observations, think about ways to improve your boat. for example:
   1. The boat in the video above has a completely flat hull. Can we create a more three-dimensional, shaped hull like a real boat?
   2. Can I add it? ladder Does that help the boat straighten?
   3. Can you build a paddle with two or more blades, like a real paddle boat?
   4. What happens if you wrap the rubber band more tightly, or if you use another rubber band?
5. Improve your boat and try again. Repeat and test the design until you are satisfied with the performance of your boat.

Variations

• The boats in this project have not been waterproof for a very long time. If they are soaked in the water for too long, they may fall apart or start to bend. Can you design a completely waterproof boat?
• Can you make a 3D printed boat instead of making it with craft supplies?
• See these two videos for examples of more complex designs built with popsicle sticks.

This activity is raised in cooperation Scientific companions. Find Original activity On the Science Buddies website.