If you jump from a desk and land stiff-legged on a concrete floor, the chance is good that you will break a leg. To see how this happens, consider the average force stopping your body when you drop from rest from a height of 1.00 m and stop in a much shorter distance d. Your leg is likely to break where the cross-sectional area of the bone (the tibia) is smallest. This is at a point just above the ankle, where the cross-sectional area of the bone is about 1.60 cm^2. A bone fractures when the compressive stress on it exceeds about 1.60*10^8 N/m^2. If you land on both legs, the maximum force your ankles can safely exert on the rest of your body is then about…….. 2 (1.60*10^8 N/m^2) (1.60*10^-4 m^2) = 5.12*10^4 N. Calculate the minimum stopping distance d that does not result in a broken leg if your mass is 60.0 kg. Don’t try it! Bend your knees!