Activity 5.4 Calculating Properties Solids
Introduction
Have you ever stopped to think why it is that you are able to float in water? The reason has to do with the concept of buoyancy, described by the Archimedes principle. The volume of water that your body displaces has weight. The weight of the displaced water pushes upward on you, while the weight of your body pushes down. If the weight of the displaced water pushing upward is less than your weight, then you will sink into the water to a point where equilibrium has been achieved. Equilibrium is reached when the weight of your body is equal to the weight of the volume of water that your body is displacing. At that point you are floating.
Another way to explain this is to look at density. If your average weight density, or the average amount of weight per unit volume of your body, is less than the weight density of the water, then you will float. The word average is used because skin, bone, hair, and muscle tissue all have different weight densities. If you were to drop a coin in the water, you would notice that it sinks. The weight density of metal is higher than the weight density of water; therefore, the volume of water that is displaced by the coin cannot weigh as much as the coin itself.
Engineers design vessels to travel on and under the surface of the water. Typically, these vessels are comprised mostly of metal. How is it that these vessels do not sink straight to the bottom of the sea floor? The answer again deals with weight, average density, and volume. If you were to fill a glass with water and place it in a tub full of water, the glass would sink. Like metal, glass has a weight density that is greater than water. If you were to place the same glass in a tub full of water, but with no liquid in the glass, it would float. In this case, the majority of the volume of the space that is taken up by the glass is the air on the inside of the glass, which is significantly less dense than water. Therefore, the average weight density of the glass/air is less than the weight density of water. This is the reason why ships are able to float. The majority of the volume enclosed by a ship is air. This example is only one engineering application of physics and the mathematics associated with the properties of solids.
Have you ever stopped to think why it is that you are able to float in water? The reason has to do with the concept of buoyancy, described by the Archimedes principle. The volume of water that your body displaces has weight. The weight of the displaced water pushes upward on you, while the weight of your body pushes down. If the weight of the displaced water pushing upward is less than your weight, then you will sink into the water to a point where equilibrium has been achieved. Equilibrium is reached when the weight of your body is equal to the weight of the volume of water that your body is displacing. At that point you are floating.
Another way to explain this is to look at density. If your average weight density, or the average amount of weight per unit volume of your body, is less than the weight density of the water, then you will float. The word average is used because skin, bone, hair, and muscle tissue all have different weight densities. If you were to drop a coin in the water, you would notice that it sinks. The weight density of metal is higher than the weight density of water; therefore, the volume of water that is displaced by the coin cannot weigh as much as the coin itself.
Engineers design vessels to travel on and under the surface of the water. Typically, these vessels are comprised mostly of metal. How is it that these vessels do not sink straight to the bottom of the sea floor? The answer again deals with weight, average density, and volume. If you were to fill a glass with water and place it in a tub full of water, the glass would sink. Like metal, glass has a weight density that is greater than water. If you were to place the same glass in a tub full of water, but with no liquid in the glass, it would float. In this case, the majority of the volume of the space that is taken up by the glass is the air on the inside of the glass, which is significantly less dense than water. Therefore, the average weight density of the glass/air is less than the weight density of water. This is the reason why ships are able to float. The majority of the volume enclosed by a ship is air. This example is only one engineering application of physics and the mathematics associated with the properties of solids.
Conclusion
1. What is the difference between area and volume? Volume is the amount of something inside of an object while area is the amount of space on the surface of an object.
2. What is density? Density is the amount mass in a certain amount of space represented by mass/volume. It's how dense an object is in a small space.
3. What is a “physical” property? Give examples of physical properties. A physical property is something that is observed without changing an object's form and is represented numerically.
1. What is the difference between area and volume? Volume is the amount of something inside of an object while area is the amount of space on the surface of an object.
2. What is density? Density is the amount mass in a certain amount of space represented by mass/volume. It's how dense an object is in a small space.
3. What is a “physical” property? Give examples of physical properties. A physical property is something that is observed without changing an object's form and is represented numerically.