Physics
In a diesel engine the high temperature needed to ignite the fuel is achieved by

An electrical spark
Using heat from exhaust
Compressing air in the cylinders
The battery

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Physics
Radiocarbon is produced in the atmosphere as a result of

Action of ultraviolet light from the sun on atmospheric oxygen.
Action of solar radiations particularly cosmic rays on carbon dioxide present in the atmosphere.
Lightning discharge in atmosphere.
Collision between fast neutrons and nitrogen nuclei present in the atmosphere.

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