Question

Inertia is defined as the tendency of an object to resist a change in motion. Objects moving in space tend to move in straight lines because of inertia. If this is the case, then why do planets orbit in elliptical paths?

Answer 1

Objects which tend to move in straight line when there is no other force acting on them and it is an ideal situation.
Planets tend to move in elliptical paths because of the gravitational pull of sun ( in solar system ) since the angle between their straight line motion and force of sun is right angle they sow elliptical paths of motion