First, there is SOME overlap between the logical requirements for the two. Super Speed would require substantial lower body strength, but doesn't need very much upper body strength. Super Strength would, of course, need substantial strength in both areas but depending on the type of muscle fibers (Fast Twitch vs Slow Twitch), speed may not be imparted.
As for the punching, e=mv^2. Hitting faster ramps up the energy of the impact at a higher rate than increasing the mass behind it, so a certain amount of speed in that aspect would be needed for Super Strength but that doesn't imply "Run Fast" like Super Speed.
No, the other one.
Physically speaking, with real world physics, power is necessary for speed, as you need a certain power to move a certain mass (lower mass also helps). However, strength is also about stopping power, like catching a heavy object thrown your way. And there is a difference between a fast, snappy hit, and a slow, forceful hit. One's a whip and the other's a tackle.
In fictionland they're separate concepts, though.
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Well at least until you get into Flash level super speed and with enough run up you start hitting using "relativistic" mass.
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Trope-wise, it doesn't matter how physically realistic or logical the concepts are; there's a reason we have the Required Secondary Powers article, after all.
If you want to examine more realistic examples of speed vs. strength, you have only to compare, say, an Olympic sprinter versus an Olympic weightlifter. Their physiques and their capabilities are vastly different. Nobody imagines that the weightlifter would be able to win a race, nor that the sprinter could lift a 500-pound barbell.
edited 4th Jan '15 9:17:42 PM by Fighteer
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I just wanted to ask from a logical and scientific standpoint if these tropes aren't mostly the same. I could think of a lot of characters which have both Super Strenght and Super Speed, but there are also characters which are incredible fast, jet physically weak (they couldn't punch someone very hard) and there are characters which have Super Strenght but are slow, even when they aren't extremly big or heavy. My question is basically if you could punch someone "hard" without punching "fast", or the other way around.