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Question
If you jump barefoot on a hard surface, your legs are injured. But they are not injured if you jump on a soft surface like sand or pillow. Why?
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Solution
In both the cases, change in momentum is same but the time interval during which momentum changes to zero is less in the first case. So, by `"F"="dp"/"dt"`, force in the first case will be more. That's why we are injured when we jump barefoot on a hard surface.
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