According to wikipedia:
"Medusa possesses a long, thick head of red hair; thanks to her exposure to the mutagenic Terrigen Mist, every strand of her hair has greater tensile strength, modulus of elasticity, and sheer resistance than an iron wire of the same thickness (average hair diameter: .045 inches). She possesses the psychokinetic ability to animate her hair for a number of feats, including elongating it to almost twice its normal length (Medusa's hair is approximately 6 feet (1.8 m) in length when relaxed), and using her hair to lift and move heavy weights (up to 1.6 tons); a portion of her hair must be used to anchor the rest at these greater weights, so that more than her scalp/skull is used as a brace"
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