Without the wheels, a bicycle frame has a mass of 6.55 kg. Each of the wheels can be roughly modeled as a uniform solid disk with a mass of 0.820 kg and a radius of 0.343 m. Find the kinetic energy of the whole bicycle when it is moving forward at 3.05 m/s.

Respuesta :

Answer:

KE=55.18 J

Explanation:

The angular velocity

ω [tex]=\frac{v}{r}=\frac{3.05\frac{m}{s}}{0.343m}[/tex]

The moment of inertia of one solid disk bicycle wheel is

[tex]I = \frac{1}{2}(M_w)r^{2}[/tex]

And the rotational kinetic energy of one wheel is

[tex]KE_w = \frac{1}{2}*I*w^2 \\KE_w = \frac{1}{2}*\frac{1}{2}*(M_w)*r^2*(\frac{v}{r})^2\\KE_w =\frac{1}{4}*(M_w)*v^2[/tex]

The total kinetic energy is then that of the frame and wheels plus the rotational kinetic energy.

[tex]KE = \frac{1}{2}*(M_f + 2*M_w)*v^2 + 2*\frac{1}{4} *(M_w)*v^2[/tex]

There is tow kinetic energy because are two wheels

Resolve

[tex]KE = \frac{1}{2} *(M_f + 3*M_w)*v^2[/tex]

[tex]KE = \frac{1}{2} *(6.55 kg + 3*0.820 kg)*(3.50 \frac{m}{s} )^2[/tex]

[tex]KE = 65.18 J[/tex]

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