Simple sum of forces parachute problem

[kirby27]

a 64 kg parachutist falling vertically at a speed of 6.3 m/s impacts the ground, which brings him to a complete stop in a distance of .92 m. assuming constant acceleration after his feet first touch, what is the average force exerted on the parachutist by the ground?

i know:
Vf=0
Vi=6.3
delta Y = .92

i used (Vfy)^2=(Viy)^2+2a(deltaY)

and found a = -21.57

i then used F=ma: F= (65)(-21.57)

and got -1402 N

is this right?

 

[SammyS]

Correct method.

Is the force exerted by the ground upward, or is it downward?

 

[kirby27]

i think the force exerted by the ground on the man is upward? should my answer be positive?

 

[SammyS]

I would think so.