Question

Jogging on hard surfaces with insufficiently padded shoes produces large forces in the feet and legs.

Answer 1

Answer:

Part a)

$F = 15600 N$

Part b)

force is 21.2 times more than the weight of the person

Explanation:

Part a)

As it is given that the distance after which he stopped is given as

d = 1.50 cm

here finally it stops so final speed is given as

$v_f = 0$

initial speed is given as

$v_i = 6 m/s$

now by the equation of kinematics we know that

$v_f^2 - v_i^2 = 2a d$

$0^2 - 6^2 = 2(a)(0.015)$

$a = -1200 m/s^2$

Now the force on the leg is given as

$F = ma$

m = mass of leg = 13 kg

$F = (13 kg)(-1200 m/s^2)$

$F = 15600 N$

Part b)

Force due to weight of the object

$F_g = Mg$

here we know

M = 75.0 kg

$F_g = 75(9.81)$

$F_g = 735.75 N$

Now we know that the ratio of the weight with the force on leg is given as

$\frac{F}{F_g} = \frac{15600}{735.75} = 21.2 N$

so force is 21.2 times more than the weight of the person