# If an object with a mass of 10 kg  is moving on a surface at 18 m/s and slows to a halt after  4 s, what is the friction coefficient of the surface?

Mar 3, 2016

${u}_{k} \cong 0 , 459$
${v}_{l} = {v}_{i} - a \cdot t$
$\frac{v}{2} = v - a \cdot t \text{ "v-v/2=a*t" } \frac{v}{2} = a \cdot t$
$18 = a \cdot 4 \text{ } a = \frac{9}{2} \frac{m}{s} ^ 2$
$F = m \cdot a \text{ "u_k*N=m*a" } {u}_{k} \cdot \cancel{m} \cdot g = \cancel{m} \cdot a$
${u}_{k} = \frac{a}{g} \text{ "u_k=9/(2*9,81) " } {u}_{k} \cong 0 , 459$