Physics pls help me?

Question

I've been trying to figure out how to solve this, but I can't! 

Here is the problem:Sam, with a mass of 64 kg was playing field hockey when she tripped and fell. If her initial velocity was 3.2 m/s [E] and she slid 2.8 m before coming to rest, determine the coefficient of kinetic friction between the grass and Sam.

Answer 1

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Let the coefficient of kinetic friction between the grass and Sam is µk, now by the work energy relation:

=>∆W = KE

=>F(friction) x s = 1/2mv^2

=>(µk x mg) x s = 1/2mv^2

=>µk = v^2/(2 x g x s)

=>µk = (3.2)^2/[2 x 9.8 x 2.8]

=>µk = 0.19 

Answer 2

m*V^2 = 2*m*g*μ*d

mass m cross

μ = V^2 / (2*g*d) = 3.2^2/(19.61*2.8) = 0.186