As part of GCSE Physics students learn the idea of an object that reaches terminal velocity when it is moving in a fluid. A great demonstration of this idea is through the example of objects in free fall. And what better object to think this idea through than a skydiver!
The embedded video bring this idea to life. Velocity values of an actual skydiver are given through the different phases of the journey. Right at the very start when the diver jumps off, the weight is the only force acting on the vertical plane. By using Newton’s 2nd law you can work out that the acceleration is all due to gravity at that point. As the diver gains speed due to this acceleration, the air resistance (or drag) also increases. Now the resultant force downwards is smaller and so is the acceleration. Nonetheless there is acceleration downwards and the velocity is still increasing. Eventually the drag increases so much that it is enough to counteract the weight. At this point the forces are balanced and the acceleration is zero. But by this point the diver has a substantial velocity. As such the diver will continue in free fall at a constant velocity. This is what is known as the terminal velocity.
Once the parachute is deployed, the drag increases and the resultant force is now upwards as the drag is more than the weight. This causes deceleration. At the same time the reduced velocity decreases the drag. But there is still deceleration so the diver keeps slowing down. Until the point when the drag is once again equal to the weight. The diver then reaches a second terminal velocity.
This is all explained in the video as well. So hit play on the video and be taken on a skydiving ride joined up with Physics revision. Good luck to all the Physics students taking their exams tomorrow.