The tibia bone in the lower leg of an adult human will break if the compressive force on it exceeds about 4×105n (we assume that the ankle is pushing up). suppose that someone step off a chair that is 0.40 m above the floor. if landing stiff-legged on the surface below, what minimum stopping distance does he need to avoid breaking his tibias? assume that the mass of the person is 64 kg

Distance = 6.27 x 10⁻⁴m

Explanation:

The speed just before hitting the ground may be expressed as

v = √2gh, where g is the acceleration due to gravity and h is the height

v = √(2 x 9.81 x 0.4) = 2.8 m/s

Using the work -energy theorem, we know that any work done on the object produces a change of kinetic energy in the object. Hence

Net Work = Final Kinetic Energy - Initial Kinetic Energy

The initial condition is stationary hence the initial Kinetic Energy = 0

Net Work may be written as

Net Work = Force x Distance = Final Kinetic Energy

4 x 10⁵ x d = (1/2) x mass x velocity²

d = {(1/2) x 64 x 2.8²}/(4 x 10⁵) = 6.27 x 10⁻⁴m

6.27 x 10⁻⁴m is the minimum stopping distance to avoid breaking his tibias.

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force