The question as it appears in the 07/10 edition of Specs & Techs from GlobalSpec:
Imagine if a motor scooter powered with extremely powerful electric batteries and an electric streetcar could be driven up to speeds approaching the speed of light. If measured from a point of reference that is at rest, which one (or both) will indicate that its mass has increased?
Thanks to 8320 who submitted the original question (which we revised a bit).
(Update: July 17, 8:30 AM) And the Answer is...
The answer is the
streetcar. Despite the common
misconception that the mass of a moving object always increases, approaching
infinity as the object approaches the speed of light, in actuality the mass
only increases if energy is added to it.
The motor scooter carries its own energy supply while the streetcar gets
its power from the powerhouse through the trolley wire.
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