Their difference lies in the prefix used before each root word, atom. The diatomic molecules are composed only of 2 atoms such as that of the diatomic elements: H2, O2, N2, Cl2, etc. On the other hand, polyatomic molecules are made up of three or mole atoms such as NH4+, H2SO4, etc.
The added weight of the sand puts more downward pressure on the wheels contacting the rails, which would cause the trains speed to decrease.
Electromagnetic waves need no matter to travel - they can travel through empty space (a vacuum). In a vacuum, all electromagnetic waves travel at approximately 3 x 108 m/s - which is the fastest speed possible. ...
Light traveling value through an optical Fibre is, 2 x 108 m/s. Hope that helps.
