Free Fall Sebastian Hollington. Forces when Falling… When an object is falling, various different forces are exerted upon it. When an object is falling,

Free FallFree Fall

Sebastian HollingtonSebastian Hollington

Forces when Falling…Forces when Falling…

• When an object is falling, various different forces When an object is falling, various different forces are exerted upon it.are exerted upon it.

– GravityGravity– Air ResistanceAir Resistance

• They act in opposite directions to each other and They act in opposite directions to each other and determine the speed at which an object falls.determine the speed at which an object falls.

GravityGravity

• Gravitational PullGravitational Pull is the force which draws an object is the force which draws an object down to the centre of the Earth.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 StrengthGravitational Pull = Mass × Gravitational Field Strength

Gravitational Pull = 50kg × 9.8 N/kgGravitational Pull = 50kg × 9.8 N/kg

Gravitational Pull = 490N Gravitational Pull = 490N

Air ResistanceAir Resistance

• As an object falls through the air, it collides will As an object falls through the air, it collides will millions of air molecules, which provide resistance.millions of air molecules, which provide resistance.

• Although one collision has such a small effect, Although one collision has such a small effect, millions happening per second begin to slow the millions happening per second begin to slow the falling object down.falling object down.

• The factors affecting how much air resistance there The factors affecting how much air resistance there is…is…– Surface Area (Cross-sectional)– Speed– Pressure– Temperature

Air ResistanceAir Resistance

Air ResistanceAir Resistance

Balancing the ForcesBalancing the Forces

• An object’s velocity depends on the size of each An object’s velocity depends on the size of each force applied to it and takes into account the force applied to it and takes into account the direction also.direction also.

• You can show both of these factors by calculating You can show both of these factors by calculating the the net forcenet force. (Downward Force – Upward Force). (Downward Force – Upward Force)

• If the 2 forces are equal the velocity will remain If the 2 forces are equal the velocity will remain constant. (Gravitational Pull = Air Resistance)constant. (Gravitational Pull = Air Resistance)

• If the downward force is greater than the upward, it If the downward force is greater than the upward, it will accelerate. (Gravitational Pull > Air Resistance)will accelerate. (Gravitational Pull > Air Resistance)

• If the upward force is greater than the downward, it If the upward force is greater than the downward, it will decelerate. (Gravitational Pull < Air Resistance)will decelerate. (Gravitational Pull < Air Resistance)

ParachutingParachuting

AirResistance

GravitationalPull

Stage 1 (Accelerating)

AirResistance

GravitationalPull

Stage 2 (Terminal Velocity 54m/s)

AirResistance

GravitationalPull

Stage 3 (Decelerates)

AirResistance

GravitationalPull

Stage 4 (2nd Terminal Velocity)