  We derive a 4D covariant Relativistic Dynamics Equation. This equation
canonically extends the 3D relativistic dynamics equation
$\mathbf{F}=\frac{d\mathbf{p}}{dt}$, where $\mathbf{F}$ is the 3D force and
$\mathbf{p}=m_0\gamma\mathbf{v}$ is the 3D relativistic momentum. The standard
4D equation $F=\frac{dp}{d\tau}$ is only partially covariant. To achieve full
Lorentz covariance, we replace the four-force $F$ by a rank 2 antisymmetric
tensor acting on the four-velocity. By taking this tensor to be constant, we
obtain a covariant definition of uniformly accelerated motion. This solves a
problem of Einstein and Planck.
  We compute explicit solutions for uniformly accelerated motion. The solutions
are divided into four Lorentz-invariant types: null, linear, rotational, and
general. For null acceleration, the worldline is cubic in the time. Linear
acceleration covariantly extends 1D hyperbolic motion, while rotational
acceleration covariantly extends pure rotational motion.
