Problem: Newton's First Law

Newton's First Law of Motion says that, in the absence of external forces, an object at rest stays at rest and an object in motion continues at constant velocity.

a)  If no forces act on a stationary object, can it start to move?

b)  If no forces act on a moving object, will it slow down?

c)  If no forces act on a moving object, can it turn?

d)  A spaceship is launched from Earth toward Neptune at a speed of 11.2 km/s.  After launch, the spaceship does not fire its engines or encounter any resistance to its motion in space.  What is its speed when it reaches Neptune?