Quote:
Originally Posted by Bjenks548
I believe that 67s drive train appeared to dominate was due to a few things.
-Ability to go over the bump
-Fit under the tunnel
-Had great manipulators accompanying it
-Great drivers and coaches
-I think i heard at Kettering that their entire robot only weighted 90lbs allowing them to accelerate faster then the 120lb bots
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Before we get carried away, let's examine this statement.
Let's start with the simple equation F=ma. Based on this, when you reduce your weight (and consequently mass) and keep your force the same, your acceleration should increase (which agrees with the bolded statement). However, when examined further, we find that the force does not always remain constant in the FRC world when your mass changes.
The force we're speaking about in this application is the force exerted by the drive wheels. This is limited by friction between the wheel surface and the playing surface. The frictional force is calculated as F
f=μN, where μ is the coefficient of friction and N is the normal force. Subbing this back into the first equation, we now have:
μN=ma
In most situations, the normal force is going to be a function of the mass, usually just N=mg when on a flat surface. Putting this back into the previous equation we have:
μmg=ma
Which simplifies to:
μg=a
In other words, in friction limited drivetrains (ie drive systems that have enough torque to "spin out" their wheels), acceleration is not governed by the mass of the robot, as the mass plays into both sides of the equation.