A light, flexible rope is wrapped several times around a hollow cylinder with a weight of 40 N and a radius of 0.25m that rotates without friction about a fixed horizontal axis. The cylinder is attached to the axle by spokes of a negligible moment of inertia. The cylinder is initially at rest. The free end of the rope is pulled with a constant force P for a distance of 5 m, at which point the end of the rope is moving 6 m/s. If the rope does not slip on the cylinder, what is the value of P

Respuesta :

Answer:

The value is [tex]P = 14.7 \ N[/tex]

Explanation:

From the question we are told that

    The weight of the hollow cylinder is  [tex]W = 40 \ N[/tex]

     The radius of the hollow cylinder is  [tex]r = 0.25 \ m[/tex]

       The distance which it is pulled is  [tex]d = 5 \ m[/tex]

       The velocity of the end of the rope  is  [tex]v = 6 \ m/s[/tex]

Gnerally the mass of the hollow cylinder is  

      [tex]m = \frac{W}{g }[/tex]

=>    [tex]m = \frac{ 40 }{ 9.8 }[/tex]

=>    [tex]m = 4.081 \ kg[/tex]

Generally angular displacement for the distance covered is mathematically represented as

        [tex]\theta = 2 \pi * \frac{ d } {2\pi r }[/tex]

=>     [tex]\theta = 2 \pi * \frac{ 5 } {2\pi r }[/tex]

=>     [tex]\theta = \frac{ 5 } { 0.25}[/tex]

=>   [tex]\theta =20[/tex]

Generally the torque experienced  by the hollow cylinder is mathematically represented as

     [tex]P * r = I * \alpha[/tex]

Here I  is the moment of inertia

=>   [tex]P * r = m r^2 * \alpha[/tex]

=>    [tex]\alpha = \frac{P }{ mr }[/tex]

Generally from kinematic equation

     [tex]w_f ^2 = w_i ^2 + 2\alpha \theta[/tex]

=>  [tex]w_f ^2 = w_i ^2 + 2\alpha \theta[/tex]  

Generally the  final angular velocity is mathematically

      [tex]w_f = \frac{v}{r}[/tex]

=>    [tex]w_f = \frac{ 6 }{ 0.25 }[/tex]

=>    [tex]w_f = 24 \ m/s[/tex]

Generally the  initial  angular velocity is Zero given that the hollow cylinder was at rest before rolling

     [tex]24^2 = 0^2 + 2* \frac{P}{4.081 *0.25 } * 20[/tex]

=>   [tex]24^2 = 0^2 + 2* \frac{P}{mr} * 20[/tex]

=>   [tex]P = 14.7 \ N[/tex]