Uniform circular motion: tangential velocity, centripetal acceleration

Steps:

• In uniform circular motion, speed is constant, but direction changes, requiring acceleration.
• Velocity vector is always tangent to the circular path at any point.
• Acceleration is centripetal, directed radially inward toward the center (Sun).
• Match arrows: tangential direction for velocity, inward radial for acceleration.

Why D is correct:

• Velocity R aligns with the tangential direction, and acceleration Q points inward, per centripetal acceleration definition $\vec{a} = -\frac{v^2}{r} \hat{r}$.

Why the others are wrong:

• A: Velocity P is likely radial, but velocity must be tangential.
• B: Velocity Q is inward radial, but velocity is perpendicular to radius.
• C: Acceleration O is probably tangential, but acceleration is always radial inward.

Final answer: D