Answer:
The shape of planetary orbits affects their orbital velocity because the speed of a planet in its orbit is not constant. According to Kepler's laws of planetary motion, the planets move in elliptical orbits with the sun at one of the two foci of the ellipse.
Kepler's second law, also known as the law of equal areas, states that a line that connects a planet to the sun sweeps out equal areas in equal times as the planet travels around the sun. This means that a planet's speed varies throughout its orbit.
When a planet is closer to the sun (at perihelion), it travels faster as it is subject to a stronger gravitational pull. Conversely, when a planet is farther from the sun (at aphelion), it travels slower due to the weaker gravitational pull.
Therefore, the shape of a planet's orbit determines its distance from the sun and, consequently, the strength of the gravitational force acting on it, which in turn affects its orbital velocity.