Question

The space probe Deep Space I was launched on October 24, 1998. Its mass was 474 kg. The goal of the mission was to test a new kind of engine called an ion propulsion drive. This engine generated only a weak thrust, but it could do so over long periods of time with the consumption of only small amounts of fuel. The mission was spetacularly successful. At a thrust of 49 mN how many days were required for the probe to attain a velocity of 850 m/s (1902 mi/h), assuming that the probe started from rest and that the mass remained nearly constant?

Answer 1

F = 49 mN = 49*10^-3 N
a = F/M = 1.04*10^-4 m/s^2

To achieve V = 850 m/s, you need a time
t = V/a = 8.2*10^6 s = 95 days