Density = mass/volume. 5000/50= 100 grams per cubic centimeter. No substance on Earth has anywhere near that density. Tops is about 20 for osmium and gold.
Answer:
Heat energy does not cool. Objects cool. Energy is not an object. Now, what happens when an object cools is that it gives off some of its thermal energy by one or more mechanisms: radiation, conduction, or convection. In radiation the energy escaped the object as electromagnetic waves - you see the red hot poker slowly dim as it cools, in conduction the energy is transferred Mechanically by the atoms of the hot object being in physical contact with those of the cool object and in convection the hot material moves to a cooler region where it gives up its heat energy by either radiation or conduction.
The acceleration should be a gain of 2 km/h per second
Electromagnetic waves can travel in vaccum but mechanical wave does not