A 1.7-kg block of wood rests on a rough surface. A 0.011-kg bullet strikes the block with a speed of 670 m/s and embeds itself. The bullet-block system slides forward 2.4 m before coming to rest.

Respuesta :

What is the coefficient of kinetic friction between the block and the surface?  Express your answer using two significant figures.

Answer:

0.39

Explanation:

Given information

m1=1.7 Kg

m2=0.011 Kg

v2=670 m/s

d=2.4 m

m2v2=(m1+m2)v hence [tex]v=\frac {m2v2}{m1+m2}[/tex] and also [tex]a=\frac {v^{2}}{2d}[/tex]

The deceleration due to friction is given by

[tex]F=\mu_k N=\mu_k W=\mu_k (m1+m2)g[/tex]

[tex]F=(m1+m2)a=\mu_k (m1+m2)g[/tex] therefore [tex]a=\mu_k g[/tex]

Therefore, [tex]a=\frac {v^{2}}{2d}=\mu_k g[/tex]

[tex]\mu_k=\frac {1}{2dg}(\frac {m2v}{m1+m2})^{2}=\frac {1}{2*2.4*9.81}\times (\frac {0.011*670}{1.7+0.011})^{2}[/tex]

[tex]\mu_k=0.39[/tex]