20.23 Isothermal compression of a gas

In post 20.20 we looked at isotropic compression of a solid object. In a gas, or a liquid, the pressure acts equally in all directions (post 17.5), so when a gas is compressed it is subjected to isotropic compression. Then resistance to compression is then given by the bulk modulus of the gas (post 20.20).… Continue reading 20.23 Isothermal compression of a gas

20.22 Relationship between Young’s modulus and shear modulus

In post 20.20, we saw that there was a relationship between the Young’s modulus, E (post 20.2) and the bulk modulus, B (post 20.19) of a material. The relationship is given by E = 3B(1 – 2ν)                     (1) where ν is the Poisson’s ratio (post… Continue reading 20.22 Relationship between Young’s modulus and shear modulus

20.21 Relationship between Young’s modulus and bulk modulus

In post 20.20, we anticipated that there must be some relationship between the Young’s modulus, E (post 20.2) and the bulk modulus, B (post 20.20) of a material. The relationship is given by E = 3B(1 – 2ν)                     (1) where ν is the Poisson’s ratio (post 20.5) of the material. We shouldn’t be surprised by… Continue reading 20.21 Relationship between Young’s modulus and bulk modulus

20.20 Deformation of objects – isotropic compression

Before you read this, I suggest you read post 20.2. Let’s think about a solid sphere surrounded by a fluid (post 16.37). If the pressure in the fluid increases, the force on the ball increases because pressure is simply a component of a force divided by an area (post 17.5). We will assume that the… Continue reading 20.20 Deformation of objects – isotropic compression

20.19 Deformation of objects – changes in shape

In post 20.2 we saw that forces can change the dimensions of an object; they can also change its shape. Change in shape without changes in dimensions is called shear. The picture above shows a cube ABCDEFGH. Let’s think about what happens when we apply a force f (posts 17.2) perpendicular to the line BF… Continue reading 20.19 Deformation of objects – changes in shape