They are said to be directly related.
a) directly related.
This is Charles' Law.
Solution :
When the spacecraft is at halfway point, the distance from the Earth as well as Mars are same. We have to account the masses of the planets. The gravitational force that is exerted by the Earth is greater because of its combined mass with the space probe.
The mass of Earth is greater than the mass of Mars. Therefore, the force of Earth is more than Mars.
Kinetic energy = 1/2 m v^2 = 1/2 x1.5 x10^-3 x 0.36
I believe it would be 2m/s.
