![]() ![]() For a single particle rotating around a fixed axis, this is straightforward to calculate. However, because kinetic energy is given by K = 1 2 m v 2 K = 1 2 m v 2, and velocity is a quantity that is different for every point on a rotating body about an axis, it makes sense to find a way to write kinetic energy in terms of the variable ω ω, which is the same for all points on a rigid rotating body. (credit: Zachary David Bell, US Navy)Įnergy in rotational motion is not a new form of energy rather, it is the energy associated with rotational motion, the same as kinetic energy in translational motion. However, most of this energy is in the form of rotational kinetic energy.įigure 10.17 The rotational kinetic energy of the grindstone is converted to heat, light, sound, and vibration. This system has considerable energy, some of it in the form of heat, light, sound, and vibration. ![]() Sparks are flying, and noise and vibration are generated as the grindstone does its work. Figure 10.17 shows an example of a very energetic rotating body: an electric grindstone propelled by a motor. However, we can make use of angular velocity-which is the same for the entire rigid body-to express the kinetic energy for a rotating object. We know how to calculate this for a body undergoing translational motion, but how about for a rigid body undergoing rotation? This might seem complicated because each point on the rigid body has a different velocity. Rotational Kinetic EnergyĪny moving object has kinetic energy. With these properties defined, we will have two important tools we need for analyzing rotational dynamics. In this section, we define two new quantities that are helpful for analyzing properties of rotating objects: moment of inertia and rotational kinetic energy. So far in this chapter, we have been working with rotational kinematics: the description of motion for a rotating rigid body with a fixed axis of rotation. Calculate the angular velocity of a rotating system when there are energy losses due to nonconservative forces.Use conservation of mechanical energy to analyze systems undergoing both rotation and translation.Explain how the moment of inertia of rigid bodies affects their rotational kinetic energy.Define the physical concept of moment of inertia in terms of the mass distribution from the rotational axis.Describe the differences between rotational and translational kinetic energy.But keep in mind the robot's axis of rotation isn't always the robot's geometric center, and in the case of a dropped center drive, it changes.By the end of this section, you will be able to: Other programs should have it in similar places. Offhand, I believe Solidworks shows the MOI about the origin axes in "Mass Properties" and Inventor has it in "iProperties / Physical". Also, the inertia of components is probably negligible compared to other masses - if you're robot's accelerating, it'll be the 100+ lbs above the drivetrain really affecting your motion, not the ~10 lbs of wheels and gears that matter.Įither way, you can calculate the moment of inertia using formulas like the ones in the page I linked, though those only work for nice shapes, or in CAD. Seems close enough to what's given in the documentation. ![]() Running the numbers for a max-weight, typical-size robot (modelled as a cube, formula from here), the moment of inertia I found was around 6 kg-m 2. I think it's asking for the moment of inertia of the robot turning about its axis. Rules are interpreted and applied by the moderation staff, and decisions made are final.Refrain from making posts or comments of a political nature.Be respectful and appropriate to all other members of this sub-reddit.All posts must be directly related to FRC or other FIRST programs.No donation posts ( with notable exceptions).Each season ends with an exciting FIRST Championship.” Rules Volunteer professional mentors lend their time and talents to guide each team. It’s as close to real-world engineering as a student can get. High-school student participants call it “the hardest fun you’ll ever have.” Under strict rules, limited resources, and an intense six-week time limit, teams of 20 or more students are challenged to raise funds, design a team "brand," hone teamwork skills, and build and program industrial-size robots to play a difficult field game against like-minded competitors. From FIRST’s website “We call FIRST Robotics Competition the ultimate Sport for the Mind. Welcome to the sub-reddit for the international First Robotics Competition (FRC).
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