A sphere. It has minimum surface area per volume.
The shape reduces drag when in water, allowing the animal to propel itself most efficiently.
styro
The most effective heat pipe working fluids for optimal thermal performance are typically water, ammonia, and acetone. These fluids have high thermal conductivity and are able to efficiently transfer heat within the heat pipe system.
Most kettles are shiny because the shiny surface reflects heat more efficiently, helping the water to boil faster. Black surfaces tend to absorb more heat, which could make the kettle less energy-efficient and take longer to heat up the water.
The amount of water in a container will affect how fast it heats up. If there is a small amount of water in a container the water will biol/heat faster. However, if there is a big amount of water it will take longer for the heat to reach all parts of the water resulting in a longer time for the water to boil/heat
Aluminum
We cannot assess the efficiency of a geometrical shape unless we have a particular purpose in mind. You will have to state what you wish to efficiently do, by means of a geometrical figure.
Water is most dense in the heat or hotness
water loses it's most heat because the stored in the water gets out in steam.
A teardrop is the most aerodynamically effective shape for a rocket travelling through the atmosphere. From an engineering standpoint, a cylindrical shape accommodates compressed gas cylinders (fuel and oxygen) most efficiently. For a rocket operating outside the atmosphere, shape is irrelevant because it will not encounter drag no matter how un-aerodynamic the shape.
Rocks are generally better at absorbing heat efficiently compared to sand and soil due to their higher density and thermal conductivity. Rocks have the ability to store and retain heat for longer periods of time compared to sand and soil which tend to dissipate heat more quickly.
Most of the heat travels through convection in water when it is being heated in a pan. As the water is heated, the warmer water rises to the top of the pan while the cooler water sinks to the bottom, creating a convection current that helps to distribute the heat throughout the water.