- #1
Faiza
- 96
- 0
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!
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!