Talk:Scrambler

Page Structure
Most of this page is written well; however, some of the extensive physics analysis of the event obscures the information about the event itself in some cases (especially since Scrambler is both a B and C event). Also, some sections have very large blocks of text without much in terms of headers to aid in navigating the page. If there is a way to bring the information about the event itself and constructing the device out to a more prominent location, and/or organize the page so the physics applications and/or information from past years are in their own sections, that would be ideal. EastStroudsburg13 (talk) 03:20, 7 August 2017 (UTC)

The physics in the wheels section is very funky. In particular, it never expands I=mr^2 and in fact radius has little effect since w=v/r. I am not an expert on the field, however. Can someone good with mechanics read over the revision? It is much shorter and should be easier to work with :) Physics Theory of the wheel

The wheel's mass, specifically its rotational inertia, is one of the most important for a scrambler: the rotational energy of the wheel does not accelerate the scrambler forward. Let [math]\omega, v, r, m, I[/math] denote the angular velocity, translational velocity, radius, mass and moment of inertia of the wheel, respectively. Since [math]\omega = \frac{v}{r}[/math] and [math]I=mr^2[/math] if we approximate wheels as hollow cylinders,

[math]E = I\omega ^2=\frac{mr^2v^2}{r^2}=mv^2.[/math]

Therefore, given a constant starting energy, an increase in mass will cause the scrambler to have less translational kinetic energy. Since [math]m\propto r[/math], smaller wheels make the car go faster. Wheels that are solid disks have moment of inertia [math]I=\frac12mr^2[/math], but have much more mass and is therefore ineffective.

A larger wheel have different benefits. Smaller wheels allow for your scrambler to move faster, but they are more susceptible to axle friction because the wheel-to-axle ratio is lower. Scramblers with small wheels may fail to reach the target distance just because of friction. Ways to reduce this friction will be discussed shortly. Teams with large wheeled scramblers move slower, but at roughly constant speeds. The wheel radius is also important to one of the integrated mass scramblers discussed later.

The second important aspect of a wheel in a scrambler is its traction. Traction, also known as static friction, is important for the car's stability, and when the wheels are used as brakes, for its braking. The friction between the wheel and the ground is static friction, unless the wheel is skidding. Since the weight of the car is supported by the wheels, the traction is at most

[math]f_s = m g \mu_s,\qquad ma=mg\mu_s, a=m\mu_s,[/math]

where [math]f[/math] is the force of friction, [math]m[/math] is the mass that the wheel supports, [math]\mu_s[/math] is the coefficient of static friction and [math]a[/math] is the acceleration of the scrambler. Beyond the maximum acceleration, the cart will start skidding.

Therefore, the wheel should have higher coefficient of friction to increase its maximum possible acceleration before skidding.

--Raxu (talk) 20:38, 28 August 2017 (UTC)