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725 
 
 
PROBLEM 13.142 
The last segment of the triple jump track-and-field event is the 
jump, in which the athlete makes a final leap, landing in a 
sand-filled pit. Assuming that the velocity of a 80-kg athlete 
just before landing is 9 m/s at an angle of 35° with the 
horizontal and that the athlete comes to a complete stop in 
0.22 s after landing, determine the horizontal component of 
the average impulsive force exerted on his feet during landing. 
 
SOLUTION 
 
 
80 kg
0.22 s
m
t
=
Δ =
 
 1 2( )m t m+ − Δ =v P W v 
Horizontal components 
 
(9)(cos 35 ) (0.22) 0
(80 kg)(9 m/s)(cos 35 )
2.6809 kN
(0.22 s)
H
H
m P
P
° − =
°= = 2.68 kNHP = 