Each wheel of a 320 kg motorcycle is 52 cm in diameter and has rotational inertia 2.1 kg m2 . The cycle and its 75 kg rider are coasting at 85 km/h on a flat road when they encounter a hill. If the cycle rolls up the hill with no applied power and no significant internal friction, what vertical height will it reach

Respuesta :

Answer:

The value is  [tex]h = 32.91 \ m[/tex]

Explanation:

From the question we are told that

    The diameter of each wheel is  [tex]d = 52 \ cm = 0.52 \ m[/tex]

    The mass of the motorcycle is  [tex]m = 320 \ kg[/tex]

    The rotational kinetic inertia is  [tex]I = 2.1 \ kg \ m^2[/tex]

    The  mass of the  rider is  [tex]m_r = 75 \ kg[/tex]

     The  velocity is  [tex]v = 85 \ km/hr = 23.61 \ m/s[/tex]

      Generally the radius of the wheel is mathematically represented as

      [tex]r = \frac{d}{2}[/tex]

=>     [tex]r = \frac{0.52}{2}[/tex]

=>    [tex]r = 0.26 \ m[/tex]

Generally from the law of energy conservation

     Potential energy  attained  by  system(motorcycle and rider )  =  Kinetic  energy of the system  +  rotational kinetic energy of  both wheels of the motorcycle

=>  [tex]Mgh = \frac{1}{2} Mv^2 + \frac{1}{2} Iw^2 + \frac{1}{2} Iw^2[/tex]

=>    [tex]Mgh = \frac{1}{2} * Mv^2 + Iw^2[/tex]

Here  [tex]w[/tex] is the angular velocity which is mathematically represented as

     [tex]w = \frac{v }{r }[/tex]

So

    [tex]Mgh = \frac{1}{2} * Mv^2 + I \frac{v}{r} ^2[/tex]

Here [tex]M = m_r + m[/tex]

         [tex]M = 320 + 75[/tex]

          [tex]M = 395 \ kg[/tex]

[tex]395 * 9.8 * h = 0.5 * 395 * (23.61)^2 + 2.1 *[\frac{ 23.61}{ 0.26} ] ^2[/tex]

=>   [tex]h = 32.91 \ m[/tex]