Falling

• This calculator works out how long it takes to fall a certain distance, and how fast you will be moving.

• It ignores air resistance (see Terminal Velocity below).

• Contrary to popular belief - heavier objects don’t fall any quicker than lighter ones (in the absene of air resistance). See this video of an Astronaught dropping a hammer & feather on the moon.

• Terminal Velocity is the highest speed reached by an object as it falls through air - it occurs when the air resistance (drag force) is equal to the downward force of gravity.

• Terminal velocity for a human depends mostly on your position.

  • The classic sky-diving position of belly down arms out has a terminal velocity of approx 195 km/h, 120 mph or 54 m/s. This will occur after a 450m (1,500ft) fall lasing 12 seconds.
  • If you pull in your arms and legs then your terminal velocity increases to 320 km/h, 200 mph or 90 m/s.
  • This calculator allows for air resistance in free fall and shows that at 25m the difference (in speed) to be ~ 4%, at 50m 7.7% and 100 m 14.5%.
  • Once you get close or above 440 meters th
  • If you fall off the nose of El Capitan it’s about 880 meters to the bottom. Taking wind resistance into account free climber Alex Honnold would have 20 seconds to consider his fate before impact.

• Smaller animals (e.g. mice) often have a low terminal velocity due to a small mass to surface area ratio. Coupled with low kinetic energy when they impact means that they can often survive uninjured from a fall from greight heights.

• The terminal velocity of an Ant, for example, is just 6.4 km/h

Calculator

You can enter any value and it will calculate the others, e.g. you can put in 20m to see the time taken to fall that distance or 50mph to see the height needed to gain that speed.

Formula

• h = height in meters
• The force of gravity g = 9.8 m/s²
  • This is 9.8 meters per second, per second
  • So after 1 second you’re falling at 9.8 meters per second (m/s)
  • After 2 seconds you’re falling at 19.7 m/s etc.
• Time to fall (s) = √( 2 x h / 9.8)
• Speed at impact (m/s) √( 2 * g * h )

Example heights

• Average height of a man in the USA - 1.75m
• Tallest man (Robert Wadlow) - 2.72m
• Standard celing height in a house - 2.4m
• Diving boards - usulaly at 1m and 3m. Often a platform at 5m and in olympic dive pools 7.5 and 10m.
• Height of a 2 story house - 5m to the top floor window sill, 8.5m to the ridge of the roof
• Height of a tall building - each storey is around 4.3m but this can vary widely.
• The worlds tallest building, the Burj Khalifa has 163 stories and is 828m
• The Nose - El Capitan has an 880m altitude gain.
• Mount Everest - 8848m