Free Fall Sebastian Hollington

Forces when Falling… When an object is falling, various different forces are exerted upon it. When an object is falling, various different forces are exerted upon it. –Gravity –Air Resistance They act in opposite directions to each other and determine the speed at which an object falls. They act in opposite directions to each other and determine the speed at which an object falls.

Gravity Gravitational Pull is the force which draws an object down to the centre of the Earth. Gravitational Pull is the force which draws an object down to the centre of the Earth. It is affected by 2 factors. It is affected by 2 factors. – –Mass of the Object (How many atoms the object contains) – –Gravitational Field Strength (How strongly the mass is pulled) The Gravitational Field Strength on Earth is 9.8 N/kg. The Gravitational Field Strength on Earth is 9.8 N/kg. Gravitational Pull = Mass × Gravitational Field Strength Gravitational Pull = 50kg × 9.8 N/kg Gravitational Pull = 490N

Air Resistance As an object falls through the air, it collides will millions of air molecules, which provide resistance. As an object falls through the air, it collides will millions of air molecules, which provide resistance. Although one collision has such a small effect, millions happening per second begin to slow the falling object down. Although one collision has such a small effect, millions happening per second begin to slow the falling object down. The factors affecting how much air resistance there is… The factors affecting how much air resistance there is… – –Surface Area (Cross-sectional) – –Speed – –Pressure – –Temperature

Air Resistance

Balancing the Forces An object’s velocity depends on the size of each force applied to it and takes into account the direction also. An object’s velocity depends on the size of each force applied to it and takes into account the direction also. You can show both of these factors by calculating the net force. (Downward Force – Upward Force) You can show both of these factors by calculating the net force. (Downward Force – Upward Force) If the 2 forces are equal the velocity will remain constant. (Gravitational Pull = Air Resistance) If the 2 forces are equal the velocity will remain constant. (Gravitational Pull = Air Resistance) If the downward force is greater than the upward, it will accelerate. (Gravitational Pull > Air Resistance) If the downward force is greater than the upward, it will accelerate. (Gravitational Pull > Air Resistance) If the upward force is greater than the downward, it will decelerate. (Gravitational Pull < Air Resistance) If the upward force is greater than the downward, it will decelerate. (Gravitational Pull < Air Resistance)

Parachuting

Air Resistance Gravitational Pull Stage 1 (Accelerating)

Air Resistance Gravitational Pull Stage 2 (Terminal Velocity 54m/s)

Air Resistance Gravitational Pull Stage 3 (Decelerates)

Air Resistance Gravitational Pull Stage 4 (2 nd Terminal Velocity)