A 25.0-kg box is released on a 27° incline and accelerates down the incline at 0.30 m/s2. Find the friction force impeding its motion. What is the coefficient of kinetic friction?

Respuesta :

Answer:

(A) Frictional force will be 103.7276 N

(B) Coefficient of friction [tex]\mu _k=0.4751[/tex]

Explanation:

We have given

mass of the box m = 25 kg

Angle [tex]\Theta =27^{\circ}[/text]

Acceleration [tex]a=0.3m/sec^2[/tex]

Apply Newton's second law of motion ,

Vertically :

            [tex]F_N[/tex]= mg cosθ

                = [tex]25\times 9.8\times COS27^{\circ}=218.296N[/tex]

Horizontally :

              mg sinθ - F = ma

A)

frictional force F= mg sinθ - ma

                        = [tex]25\times 9.8sin27^{\circ}-25\times 0.3=103.7276N[/tex]

B)

Coefficient of friction  [tex]\mu _k=\frac{F}{F_N}=\frac{103.7276}{218.296}=0.4751[/tex]

Ver imagen aristeus

The frictional force impeding the motion of the box is 103.73 N

The coefficient of friction is 0.48

The given parameters;

  • mass of the box, m = 25 kg
  • angle of inclination, = 27°
  • acceleration of the box, a = 0.3 m/s²

The vertical component of the force on the box is calculated by applying Newton's second law of motion;

[tex]F_n = mg\times cos(\theta)\\\\F_n = 25\times 9.8 \times cos(27)\\\\F_n = 218.3 \ N[/tex]

The frictional force is determined by resolving the horizontal component of the force on the box;

[tex]\Sigma F_{||} = 0\\\\mgSin(\theta) - F_k = ma\\\\F_k = mg\times sin(\theta) - ma\\\\F_k = 25\times 9.8 \times sin(27) - (25\times 0.3)\\\\F_k = 103.73 \ N[/tex]

The coefficient of friction is calculate as;

[tex]\mu_k = \frac{F_k}{F_n} \\\\\mu_k = \frac{103.73}{218.3} \\\\\mu_k = 0.48[/tex]

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