Answer:
Part A: 7.75 m/s
Part B: 2330.8 kN
Part C: 24.03 kN
Part D: 4.8 kN
Part E: 
Part F: Option D
Bending one's legs lengthens the duration of force application from the ground, resulting in a reduction of the applied force.
Explanation:
Part A
Using the fundamental kinematic equations
where v represents the velocity just before ground impact, g denotes gravitational acceleration, u signifies initial velocity, and h is the fall height.
With the initial velocity at zero, thus:


Plugging in 10 m/s² for g and 3 m for h gives:

Part B
The force exercised by the leg can be expressed as
F = PA where P is pressure, F indicates force, and A denotes the cross-sectional area of the bone.

With a substitution of 2.3 cm or 0.023m for d and
for P, we derive the force as:

Part C
The fundamental kinematic equations from part (a) can also be rearranged to show:
and solving for a yields
where a is the acceleration and
signifies the change in length.
Using the previously derived value from part a, 7.75 m/s for v, and 0.01 m for
gives us:

The force felt by the man is given by:

Part D
A similar approach with the fundamental kinematic equations shows:
and solving for a indicates:
where a is the acceleration and
denotes the change in height.
The force experienced can thus be defined as
.
For substitution, we use m = 80 Kg, and 0.5m for \triangle h along with other values calculated in part c.

Part E

Part F
Bending one's legs extends the period over which the force acts, thus lessening the overall force exerted by the ground.