(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

2. Relevant equations

W = ΔUg + ΔkE + ΔUs

KE = 0.5 m v^2

Ug = m g h

Us = 0.5 k x^2

3. The attempt at a solution

k = 60 N/m vi=0 m/s (" the block is released from rest ") xi= 0 m/s ( "the spring is unstreached") vf= 0 m/s xf= 0.2 * sin 37 = 0.2*0.6 = 0.12 m d= 0.2 m hf=0 hi= 0.2*sin37 = 0.12m m= 2 kg μκ = ?

W = Fκ d cos θ

Fk = FN μk

Fk = mg cos θ ( mg must be decompose)

Fk = 2*10*0.8 = 16 N

so , W = 16 * 0.2 * cos 180 * μκ = - 3.2 μκ

W = ΔUg + ΔkE + ΔUs

since the velocity is constant , ΔkE = 0 --> W = Δ Us + ΔUg

- 3.2 μκ = 0.5 k xf^2 - 0.5 * k xi^2 + mghf - mghi

- 3.2 μκ = 0.5 * 60 * ( 0 )^2 - 0.5*60*( 0.12 )^2 + 2*10*0 - 2*10*0.12

- 3.2 μκ = -0.432 - 2.4

- 3.2 μκ = -2.832

μκ = 0.885

This is my tried , but I don't know where is my mistake.

Any help would be greatly appreciated !

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# Homework Help: How to get the coefficient of kinetic friction

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