Falling Objects D. Crowley, 2008

Wednesday, April 19, 2017 Falling Objects To be able to describe the changes in forces on a falling object Joseph Kittinger – 102’000ft above Earth

Forces What are the forces on a skydiver? How do these forces change (think about when they first jump out; during free fall; and when the parachute has opened) What happens if the skydiver changes their position The skydiver’s weight (which depends on gravity) remains the same throughout the jump But their air resistance changes depending upon what they’re doing

Parachutes Changing position whilst skydiving causes massive changes in air resistance, dramatically affecting how fast you fall…

Skydiving Stages Complete the skydiving stages worksheet Label the forces Draw correctly sized force arrows Write a sentence explaining the forces experienced by the skydiver during the descent

Skydiving Stages Stage 1 – after just jumping from the plane the skydiver is not moving very fast – their weight is a bigger force than their air resistance, so they accelerate downwards

Skydiving Stages Stage 2 – Eventually the force of the air resistance has increased so much that it is the same size as the skydiver’s weight – the forces are balanced and the speed remains constant (this is terminal velocity)

Skydiving Stages Stage 3 – When the chute opens air resistance increases dramatically: the air resistance force is much greater than the weight force, so the skydiver slows down

Skydiving Stages Stage 4 – As the skydiver slows, the air resistance force from the chute is reduced, until it is the same size as the weight force – the forces are balanced and the speed remains constant (this is a new terminal velocity)

Skydive

Directional

Terminal Velocity When vehicles and free-falling objects first move they have much more force accelerating them than resistance which is trying to slow them As speed increases resistance builds up – gradually reducing the acceleration Eventually the resistance forces is equal to the accelerating force and the object remains at a constant speed (terminal velocity) Apollo 15 parachutes

New, lower terminal velocity reached Velocity-Time Graph Parachute opens – diver slows down Speed increases… Terminal velocity reached… Velocity Diver hits the ground New, lower terminal velocity reached Time