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1. Two identical bowling balls of mass M and radius R roll side by side at speed v0 along a flat surface. Ball 1 encounters a ramp of angle θ that has a tacky surface and rolls up without slipping until it reaches a maximum height h1. Ball 2 encounters a ramp of angle θ that has a frictionless surface which it ascends to a maximum height h2. What is the ratio of h1/h2 in terms of M, v0, θ, g, and R?

Respuesta :

Answer:

1/2

Explanation:

We need to make a couple of considerations but basically the problem is solved through the conservation of energy.  

I attached a diagram for the two surfaces and begin to make the necessary considerations.

Rough Surface,

We know that force is equal to,

[tex]F_r = mgsin\theta[/tex]

[tex]F_r = \mu N[/tex]

[tex]F_r = \mu mg cos\theta[/tex]

Matching the two equation we have,

[tex]\mu N = \mu mg cos\theta[/tex]

[tex]\mu = tan\theta[/tex]

Applying energy conservation,

[tex]\frac{1}{2}mv^2_0+\frac{1}{2}I_w^2 = F_r*d+mgh_1[/tex]

[tex]\frac{1}{2}mv^2_0+\frac{2}{5}mR^2\frac{V_0^2}{R^2} = F_r*d+mgh_1[/tex]

[tex]\frac{1}{2}mv^2_0+\frac{mv_0^2}{5} = mgsin\theta \frac{h_1sin\theta}+mgh_1[/tex]

[tex]\frac{v_0^2}{2}+\frac{v_0^2}{5} = gh_1+gh_1[/tex]

[tex]h_1 = \frac{1}{2g}(\frac{v_0^2}{2}+\frac{v_0^2}{5})[/tex]

Frictionless surface

[tex]\frac{1}{2}mv_0^2+\frac{1}{2}I\omega^2 = mgh_2[/tex]

[tex]\frac{1}{2}m_v^2+\frac{1}{2}\frac{2}{5}mR^2\frac{v_0^2}{R^2} =mgh_2[/tex]

[tex]\frac{v_0^2}{2}+\frac{v_0^2}{5} = gh_2[/tex]

[tex]h_2 = \frac{1}{g}(\frac{V_0^2}{2}+\frac{v_0^2}{5})[/tex]

Given the description we apply energy conservation taking into account the inertia of a sphere. Then the relation between [tex]h_1[/tex] and [tex]h_2[/tex] is given by

[tex]\frac{h_1}{h_2} = \frac{\frac{1}{2g}(\frac{v_0^2}{2}+\frac{v_0^2}{5})}{\frac{1}{g}(\frac{V_0^2}{2}+\frac{v_0^2}{5})}[/tex]

[tex]\frac{h_1}{h_2} = \frac{1}{2}[/tex]

The presence of friction enables the the ball to roll higher up the hill by

converting its rotational kinetic energy into potential energy.

[tex]\underline{\mathrm{The \ ratio \ of \ \dfrac{h_1}{h_2} \ is \ \dfrac{7}{5}}}[/tex]

Reasons:

The initial kinetic energy of each ball are given as follows;

Work done by ball rolling up a hill without slipping.

For the bowling ball that rolls up the hill without slipping, we have;

[tex]\dfrac{1}{2} \cdot (c + 1) \cdot M \cdot v_0^2 = \mathbf{M \cdot g \cdot h}[/tex]

Where, for a sphere, [tex]c = \dfrac{2}{5}[/tex]

Therefore;

[tex]\dfrac{1}{2} \cdot \left(\dfrac{2}{5} + 1 \right) \cdot M \cdot v_0^2 = M \cdot g \cdot h_1[/tex]

[tex]\mathbf{\dfrac{7}{10} \cdot v_0^2} = g \cdot h_1[/tex]

[tex]h_1 = \mathbf{\dfrac{7}{10} \cdot\dfrac{ v_0^2 }{g}}[/tex]

For the bowling hall that slides up the hill, we have;

[tex]\dfrac{1}{2} \cdot M \cdot v_0^2 = \mathbf{M \cdot g \cdot h_2}[/tex]

[tex]\dfrac{1}{2} \cdot v_0^2 = g \cdot h_2[/tex]

[tex]h_2 = \mathbf{\dfrac{v_0^2 }{2 \cdot g} \cdot}[/tex]

[tex]\mathrm{The \ ratio \ of \ \dfrac{h_1}{h_2} = \mathbf{\frac{ \dfrac{7}{10} \cdot\dfrac{ v_0^2 }{g}}{\dfrac{v_0^2 }{2 \cdot g} \cdot} }} = \dfrac{7}{10} \times 2 = \dfrac{7}{5}[/tex]

[tex]\underline{\mathrm{The \ ratio \ of \ \dfrac{h_1}{h_2} = \dfrac{7}{5}}}[/tex]

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