Acceleration = (change in speed) / (time for the change)
Acceleration = (4 m/s) / (8 seconds)
Acceleration = 0.5 m/s²
Force = (mass) x (acceleration)
Force = (85 kg) x (0.5 m/s²)
Force = 42.5 Newtons
I'll answer since there are no answers to refer to. A jovian planet is pretty much a planet that doesn't have a solid surface. It's a planet made up primarily of gases hydrogen, nitrogen, helium, methane and so on