How Surface Area Affects the Buoyancy of Wood
Introduction: The upward force on an object that is in water that allows it to float is called buoyancy. The buoyant force is always equal to the weight of the water displaced by the object in the water. This force was discovered by Archimedes, who was in his bathtub when he wondered why objects seemed lighter when he held them under the water. He found out that if an object is lighter than the weight of the water it displaces, it will float, but if it is heavier, it will sink. The force of buoyancy is important in many different areas, and especially in the making of ships. The surface area that is touching the water of the ship is very large, due to the shape of the hull, and that, beside the density of the ship, is what keeps the ship floating. An important example of how surface area affects buoyancy is when people float in the water. Everyone knows that it is much easier to stay afloat when we are lying on our backs than when we are in a standing position in the water. But how does the surface area of an object affect its buoyancy?
Aim: To investigate how changes in the surface area of pieces of wood of the same mass affects their buoyancy.
Hypothesis: That the larger the surface area of the piece of wood, the more buoyant it will be.
Variables:
The Independent Variable is the surface area of each piece of wood.
The Dependent Variable is the buoyancy of the each piece of wood.
The Controlled Variables are: o The weight of each piece of wood and its hook o The amount of water each piece of wood is measured in o The spring balance used to take measurements must be the same (to prevent any inaccuracies) o The size of the container used to hold the water
Apparatus:
4 pieces of wood attached to hooks, each weighing 100g, with different surface areas (e.g. 81cm², 96cm², 110cm², 153cm²)
A container large enough to fit each of the pieces of wood without them touching the bottom or sides (e.g. 4L ice-cream container)
Retort stand,
Aim: To investigate how changes in the surface area of pieces of wood of the same mass affects their buoyancy.
Hypothesis: That the larger the surface area of the piece of wood, the more buoyant it will be.
Variables:
The Independent Variable is the surface area of each piece of wood.
The Dependent Variable is the buoyancy of the each piece of wood.
The Controlled Variables are: o The weight of each piece of wood and its hook o The amount of water each piece of wood is measured in o The spring balance used to take measurements must be the same (to prevent any inaccuracies) o The size of the container used to hold the water
Apparatus:
4 pieces of wood attached to hooks, each weighing 100g, with different surface areas (e.g. 81cm², 96cm², 110cm², 153cm²)
A container large enough to fit each of the pieces of wood without them touching the bottom or sides (e.g. 4L ice-cream container)
Retort stand,
Bibliography: Buoyancy, Retrieved July 28th, 2007 http://encyclopedia.thefreedictionary.com/buoyancy Waterline, Retrieved July 28th, 2007 http://encyclopedia.thefreedictionary.com/Plimsol+line R. Nave, Buoyancy, Retrieved July 28th, 2007 http://hyperphysics.phy-astr.gsu.edu/hbase/pbuoy.html What Is Buoyancy?, Retrieved July 28th, 2007 from http://www.wisegeek.com/what-is-buoyancy.htm