A spacecraft is coasting toward Mars. The mass of Mars is 6.4 x 10 ²³ kg and its radius is 3400 km (3.4 x 10 ⁶ m). When the spacecraft is 8200 km (8.2 x 10 ⁶ m) from the center of Mars, the spacecraft's speed is 2400 m/s. Later, when the spacecraft is 5100 km (5.1 x 10 ⁶ m) from the center of Mars, what is its speed? Assume that the effects of Mars's two tiny moons, the other planets, and the Sun are negligible. Precision is required to land on Mars, so make an accurate calculation, not a rough, approximate calculation.

Vf = m/s