Lab · Engineering Mechanics
Rigid-Body Kinematics Lab
A planar rigid body with a prescribed acceleration of G and a prescribed angular acceleration. Every pose and rate is the exact constant-acceleration solution — nothing is integrated numerically, and no force model is implied.
Model
The rectangle is reference geometry for the figure only: it carries no mass and no inertia, and it never enters a result.
Inputs
Measured counter-clockwise from +x and converted to radians for every calculation.
Points of interest
Offsets are measured from G in the body frame, so a point stays on the body as it turns. Up to 4 points travel in a shared link.
Workspace
The cursor reads the exact solution at one instant. It changes nothing in the model and stays out of the shared link.
Body at the cursor
Select a vector, support, couple or distributed load to inspect its exact values.
G is the centre of mass. C (v = 0), when shown, is the instantaneous centre of zero velocity—not a geometric centroid.
State at the cursor
| Time t | 0 s |
|---|---|
| Position of G | (0, 0) m |
| Orientation θ | 0° (0 rad) |
| Velocity of G | (2, 0) m/s |
| Angular velocity ω | 3 rad/s |
| Acceleration of G | (0, 0) m/s² |
| Angular acceleration α | 0 rad/s² |
| Instantaneous centre | (0, 0.66667) m |
The one body point whose velocity is zero at this instant.
What this Lab models
Describes how a rigid body moves — a prescribed acceleration of G and angular acceleration, giving the pose, velocity and acceleration of any body-fixed point — without stating what mass, inertia or load would cause that motion. Compare with the Rigid-Body Dynamics Lab, which finds the motion caused by forces.
Related calculations
Continue
The pose, velocity, ω and geometry transfer exactly. A kinematic model states no mass, inertia or load, so those start from the Lab defaults and are yours to enter.
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