Answer: Air
Explanation: Of the three mediums (gas, liquid, and solid) sound waves travel the slowest through gases, faster through liquids, and fastest through solids. Air and hydrogen have nearly the same elastic properties, but the density of hydrogen is less than that of air. Sound thus travels faster (about 4 times as fast) in hydrogen than in air.
<u>Mass</u>
- Mass is measured in kilograms.
- Mass does not change when gravity changes.
- Mass is the amount of matter in something.
<u>Weight</u>
- Before I answer, we have to know weight formula. Weight = mass × acceleration due to gravity.
- Therefore, weight is measured in Newtons.
- Weight changes when gravity changes. This is because weight is dependent on acceleration due to gravity.
- Weight is a gravitational force.
Hope you could understand.
If you have any query, feel free to ask.
The piece of iron is brought from a temperature of 100C to a temperature of 22C. In this process, the heat released by this piece of iron is

where

is the mass of the piece of iron,

is the iron's specific heat, and the temperature variation is

. Using these values, the amount of heat released by the iron is

With negative sign because it is amount of heat released. This heat is then trasferred to the water, so the amount of heat absorbed by the water is Q=6.9 kJ.
The boys body will continue to move in a forward motion, the stairs an an will make the skateboard come to a complete stop because the force of the stairs is much greater, this makes in an unbalanced force. This is and example of inertia of motion.
About what elemental trip through europe