[eli5] When resultant forces are equal on a falling object, why does the object still fall

Question

When weight acting downwards is equal to air resistance acting upwards why is the object falling???

In: 0

Answer 1

Newton’s laws of motion tell us that an unbalanced external force causes an object to accelerate. It follows that an object subjected to balanced forces will maintain a constant velocity.

Imagine dropping a watermelon from an airplane. At first, the force of gravity exceeds drag, so the watermelon accelerates. As its speed increases, the force of drag increases too, so the net force on the melon is lower. It still accelerates, but at a lower rate. Eventually drag cancels out weight, and there’s no more increase in velocity – the melon is now at terminal velocity. All forces are balanced but it’s still falling at a constant velocity.