SCIENCE
Does frozen water increase in volume when it melts?
Does frozen water increase in volume when it melts?
No, the volume of frozen water does not increase when it melts.
The question can be answered in two parts:
First, when water freezes, it increases in volume to about 109%. This the opposite of most materials, that is, the solid form of most substances is more dense than their liquid form.
When ice subsequently melts, its volume changes again, but not its mass. According to Archimedes principle, the melted water from the ice cube has exactly the same weight as the water that was displaced by the ice cube when it was frozen.
The ice returns to its original volume, so it contracts, but its mass is the same as before.
The question can be answered in two parts:
First, when water freezes, it increases in volume to about 109%. This the opposite of most materials, that is, the solid form of most substances is more dense than their liquid form.
When ice subsequently melts, its volume changes again, but not its mass. According to Archimedes principle, the melted water from the ice cube has exactly the same weight as the water that was displaced by the ice cube when it was frozen.
The ice returns to its original volume, so it contracts, but its mass is the same as before.
Why do bubbles appear when we shake a bottle half-filled with water?
Why do bubbles appear when we shake a bottle half-filled with water?
Bubbles appear when we shake a half-full water bottle because the other half of the bottle is filled with air.
When you shake the bottle, transparent air and water are transmuted into an opaque white mass. A close look through a magnifying glass shows that the foam consists of bubbles of various sizes.
The clear liquid turns into a mass of bubbles but they separate when you stop shaking, as water drains from between the stacked bubbles and the walls of the bubbles gets progressively weaker, eventually bursting from the effect of atmospheric pressure.
When you shake the bottle, transparent air and water are transmuted into an opaque white mass. A close look through a magnifying glass shows that the foam consists of bubbles of various sizes.
The clear liquid turns into a mass of bubbles but they separate when you stop shaking, as water drains from between the stacked bubbles and the walls of the bubbles gets progressively weaker, eventually bursting from the effect of atmospheric pressure.
What is the purpose of the stones on the MRT tracks?
What is the purpose of the stones on the MRT tracks?
The stones you see on railway tracks, such as on MRT tracks, are known as
'track ballast'.
Ballast forms the foundation on which rail tracks are laid. It helps to support the weight of the track, to distribute the weight of loading (load transfer) of passing trains onto the track, and facilitate the drainage of water.
In addition, in an extract from Encyclopaedia Britannica, one of the eDatabases available via NLB, it is mentioned that: "The sleepers, or crossties, to which the rails are fastened, are embedded in the ballast. This is tightly compacted or tamped around the sleepers to keep the track precisely leveled and aligned."
Ballast forms the foundation on which rail tracks are laid. It helps to support the weight of the track, to distribute the weight of loading (load transfer) of passing trains onto the track, and facilitate the drainage of water.
In addition, in an extract from Encyclopaedia Britannica, one of the eDatabases available via NLB, it is mentioned that: "The sleepers, or crossties, to which the rails are fastened, are embedded in the ballast. This is tightly compacted or tamped around the sleepers to keep the track precisely leveled and aligned."