1. © Oxford University Press 2009 12.4b Terminal velocity At first the parachutist accelerates at 10m/s 2 due to gravity.

2. © Oxford University Press 2009 But as she gets faster she hits more air particles each second. The more air particles she hits the greater the air resistance. This stops her increasing speed as quickly. 12.4b Terminal velocity

3. © Oxford University Press 2009 When the upwards force of air resistance equals the weight of the parachutist the forces on her are balanced so she travels at a constant speed – terminal speed. 12.4b Terminal velocity

4. © Oxford University Press 2009 When the parachute opens the parachute hits lots of air molecules. The upward force of air resistance increases. She slows down (decelerates). 12.4b Terminal velocity

5. © Oxford University Press 2009 The air resistance is much larger with the parachute open. After a while air resistance equals her weight again at a much lower speed. The forces are balanced. She falls at a lower terminal speed and lands safely. 12.4b Terminal velocity

6. © Oxford University Press 2009 12.4b Terminal velocity

7. © Oxford University Press 2009 Going slowly Parachutists fall like this to increase the air resistance force so they fall more slowly and reach a lower terminal velocity. 12.4b Terminal velocity