The last segment of the triple jump tracxk and feild event is the jump, in which

Question

The last segment of the triple jump tracxk and feild event is the jump, in which the athlete makes a final leap, landing in a sand filled pit. Assuming that the velcity of a 178 lb athlete just before landing is 30 ft/s at an angle of 35 degrees with the horizontal and that the athlete comes to a complete stop in 0.22 seconds after landing, determine the horizontal component of the average impulsive force exerted on his feet during landing?





The answer should be 610 lb, but my answer always becomes 617 lb...
m=178lb
W=178lb/32.2
v=30ft/s
angle=35 degree

therefore,
-Wv*cos35=Ft
F=-(m/g)v*cos35/0.22
=-(178/32.2)30*cos35/0.22

Is this equation incorrect?
Please show me the correct way.

Explanation / Answer

Horizontal component of velocity at the time of landing = 30*Cos35 = 24.57 ft/s

His average deceleration in horizontal direction, a = (Initial velocity - Final velocity)/time taken = (24.57-0)/0.22 = 111.7 ft/s^2

Force in horizontal direction = ma = 178*111.7 = 19883 lb-ft/s^2 = 19883/32.2 lb = 617.5 lb

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