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 his legs increases the time over which the ground applies force, thus decreasing the force applied by the ground.
Explanation:
<u>Part A
</u>
From the fundamental kinematic equation
where v is the velocity of the man just before hitting the ground, g is acceleration due to gravity, u is initial velocity, h is the height.
Since the initial velocity is zero hence
Substituting 10 m/s2 for g and 3 m for h we obtain
<u>Part B
</u>
Force exerted by the leg is given by
F=PA where P is pressure, F is force, A is the cross-section of the bone
Substituting 2.3 cm which is equivalent to 0.023m for d and for P we obtain the force as
<u>Part C
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The fundamental kinematic equation is part (a) can also be written as
and making a the subject then
where a is acceleration and is the change in length
Substituting the value obtained in part a, 7.75 m/s for v, u is zero and 1cm which is equivalent to 0.01 m for then
Force exerted on the man is given by
<u>Part D
</u>
The fundamental kinematic equation is part (a) can also be written as
and making a the subject then
where a is acceleration and is the change in height
Also, force exerted on the man is given by
Substituting 80 Kg for m, 50 cm which is equivalent to 0.5m for \triangle h and other values as used in part c
<u>Part E
</u>
Part F
Bending his legs increases the time over which the ground applies force, thus decreasing the force applied by the ground