Higher the temperature the lower the density
Thermal expansion is the tendency of matter to change in volume in response to change in temperature. During thermal expansion, the density of a substance decreases as its volume increases. Volume is the space occupied by a body. So, when a substance expands on heating, it will occupy more space or will have more volume. But its mass does not change because the amount of matter contained in a body cannot change. Therefore, mass divided by increased volume gives a decreased density.
Thermal expansion is the tendency of matter to change in volume in response to change in temperature. During thermal expansion, the density of a substance decreases as its volume increases. Volume is the space occupied by a body. So, when a substance expands on heating, it will occupy more space or will have more volume. But its mass does not change because the amount of matter contained in a body cannot change. Therefore, mass divided by increased volume gives a decreased density.
Thermal expansion is the tendency of matter to change in volume in response to change in temperature. During thermal expansion, the density of a substance decreases as its volume increases. Volume is the space occupied by a body. So, when a substance expands on heating, it will occupy more space or will have more volume. But its mass does not change because the amount of matter contained in a body cannot change. Therefore, mass divided by increased volume gives a decreased density.
It increases. The volume of a material decreases in contraction, while the mass remains the same.
The density increase.
It becomes smaller.
they produce thermal energy
These gaps are thermal expansion joints, they prevent the rails from buckling when they get hot in the summer. Although modern welded rail only has these gaps every mile or so to reduce the vibration and noise of the wheel crossing them (instead of every 40 feet on unwelded rail). All construction must provide for thermal expansion (e.g. bridges have thermal expansion joints, concrete road paving has thermal expansion grooves).
During thermal shock the temperate rises or falls at an unstable rate. When this occurs it can cause the structural integrity of an object to become damaged.
refractory metals have high melting points and are used in extremely hot environments; if expansion coefficient is lower this prevents high stresses that can develop due to thermal gradients during the high heat up. It helps to have high thermal conductivity as well
To save the piping from breaking during thermal expansion (day/night, summer/winter). They provide the needed space to expand withought breaking the system.
Think of of the expanding substance as a box full of marbles. If it expands, they end up in a bigger space (in this case a bigger box). Because of that they have more room to move around and there will be less particles and less mass per cm2 which is what the density is.