PEg = Mass x Height x Gravity. So it doesn't matter how much PEg she started with, since you're finding how much it changed when she walked down 2.5 meters of stairs. So by plugging into the equation, you'll find how much potential energy was lost by walking down. (I'll leave it up to you since idk if you use 10 or 9.8 as gravity)
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Three uses that ultraviolet radiation is used for is for cleaning tools like for doctors or dentists, suntanning, and photo therapy. This can be okay and worth the risk if used carefully and with protection. Otherwise, it can cause cancer or blindness
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