Does an object moving in a circle obey the law of inertia? Which way would it move if there were no net force on it?
IT would go in a straight line, of course. A force keeps accelerating it inward.
So it does not obey the law of inertia?
Yes, an object moving in a circle still obeys the law of inertia. According to Newton's first law of motion, an object continues to move in a straight line at a constant speed unless acted upon by an external force. This means that an object in circular motion will tend to move in a straight line if there is no net force acting on it.
However, in the case of circular motion, there is always a net force acting inward towards the center of the circle, called the centripetal force, which keeps the object moving in a circular path. This force is necessary to constantly change the object's direction and prevent it from moving in a straight line.
If there were no net force acting on the object, it would simply continue moving in a straight line due to its inertia, tangentially to the circle at the point it was released from the circular path. This is known as the tangent to the circle, and it is perpendicular to the radius at that point.