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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?
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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