Why Does a Body Continue Moving When the Force Is Removed?
Imagine pushing a block across a table. You push it for a while and then stop pushing. What happens next? In everyday life, the block eventually stops. This might make us think that a force is necessary to keep an object moving. But that is not what Newton's laws tell us. The important question is: What forces are acting on the block after you stop pushing? A force is not required to maintain motion Newton's First Law states: An object continues in its state of rest or uniform motion in a straight line unless acted upon by a net external force. The key word here is net . If the net force on an object is zero, \[ \vec F_{\text{net}} = 0 \] then Newton's Second Law gives \[ \vec F_{\text{net}} = m\vec a \] Therefore, \[ \vec a = 0 \] Zero acceleration means that the velocity does not change. So, if an object is already moving with velocity \(\vec v\), it continues moving with the same velocity. In other words: A force is not re...