contestada

The coefficients of friction between the 20-kg crate and the inclined surface are µ,8 = 0.24 and J.lk = 0.22. If the crate starts from rest and the horizontal force F = 200 N, what is the magnitude of the velocity of the crate when it has moved 2 m?

Respuesta :

Answer:5.60 m/s

Explanation:

Given

Coefficient of static friction [tex]\mu _s=0.24[/tex]

Coefficient of kinetic friction [tex]\mu _k=0.22[/tex]

mass of crate [tex]m=20\ kg[/tex]

Force applied [tex]F=200\ N[/tex]

maximum static Friction [tex]F_s=\mu _sN[/tex]

[tex]N=mg[/tex]

[tex]F_s=0.24\times 20\times 9.8[/tex]

[tex]F_s=47.04\ N[/tex]

thus applied force is greater than Static friction therefore kinetic friction will come into play

[tex]F_k=\mu _kN[/tex]

[tex]F_k=0.22\times 20\times 9.8=43.12\ N[/tex]

net Force on crate [tex]F-F_k=ma[/tex]

[tex]a=\frac{200-43.12}{20}=7.84\ m/s^2[/tex]

Magnitude of velocity can be obtained by using

[tex]v^2-u^2=2as[/tex]

where v=final velocity

u=initial velocity

a=acceleration

s=displacement

here initial velocity is zero as crate start from rest

[tex]v^2-0=2\times 7.84\times 2[/tex]

[tex]v=\sqrt{31.37}[/tex]

[tex]v=5.60\ m/s[/tex]