In newton 1law of the motion said that a body at rest will remain at rest .and a body in motion will continue in a motion in a straight line with a uniform speed unless it is compelled by an external force to change its state of rest or of uniform motion. This law is saying that the object in motion will continuously move but when we through a cricket ball why it bends and comes back to earth but when we through this in straight line
In this case, an external force is acting. Here the external force acting is due to gravity.
here also a external force is acting . the external force is gravity.