Cardboard Boat: Calculating Buoyant Forces

  • Context: High School 
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    Boat Buoyant Forces
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Discussion Overview

The discussion revolves around the principles of buoyancy as they apply to constructing a cardboard boat for a race. Participants explore how to determine whether the boat will float when carrying two people, focusing on the calculations related to buoyant forces and water displacement.

Discussion Character

  • Exploratory, Technical explanation, Homework-related

Main Points Raised

  • One participant states that a boat floats when the weight of the water it displaces exceeds the weight of the boat and its occupants.
  • Another suggests calculating the volume of the boat below the waterline and multiplying it by the density of water to find the necessary displacement.
  • A method is proposed to create a rectangular boat, where the area of the bottom is used to determine how much water needs to be displaced based on the total weight of the boat and people.
  • Additional design considerations are mentioned, such as making the boat waterproof and ensuring safety measures like wearing lifejackets.

Areas of Agreement / Disagreement

Participants generally agree on the basic principle of buoyancy and the calculations involved, but there is no consensus on specific design strategies or additional considerations for the boat.

Contextual Notes

Some assumptions about the shape and dimensions of the boat are not explicitly stated, and the discussion does not resolve how to handle variations in design or weight distribution.

Who May Find This Useful

Students involved in physics projects, educators looking for practical applications of buoyancy, and hobbyists interested in boat design and construction.

chrozer
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Ok so I'm in a Physics class and there is going to be a Cardboard Boat Race competition. So I have to build a boat out of cardboard for two people to fit in and it be able to float across a length's pool. I just want to know how you would find out if a boat that I build out of cardboard would float with 2 people in it. My teacher hasn't taught us anything about these kinds of physics concepts, but she said it has something to do about buoyant forces.

So my question is how do I determine if the boat will sink or not? Instructions on what I should do? Any ideas?
 
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A boat floats when the weight of water it displaces is greater than the weight of the boat.
So you simply work out the volume of the boat below the water line (simpler if it is a simple shape!) multiply by the density of water (fresh water weighs 1000kg for each m^3)
Then add up the total weigth of the boat + the two people.

The simple way is to make a rectangular boat and calculate the area of the bottom, if you know the weight of the boat+people you can work out how much volume of water you need to displace and so work out how far up the sides the water will come - then you make the sides higher than that!
 
Any design ideas or tips?
 
Make it waterproof, avoid icebergs, wear lifejackets
 

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