• Question: Hello! My Question is: If someone was to jump of the top most point of The Shard in London, how many pillows would it take to cushion the fall?

    Asked by patek032 to Joel, Kristian, Tim, Venus, Zachary on 12 Nov 2013.
    • Photo: Kristian Harder

      Kristian Harder answered on 12 Nov 2013:

      Just one, if the pillow is big enough. 🙂 For smaller pillows, I don’t think there is a general answer. It depends on what size the pillows are, what material they are made from, whether the person jumps head first or slows down a bit by trying to remain horizontal. The best way to find out how many pillows it takes would be to make a series of experiments with crash test dummies. That’s pretty much what they are for anyway. 🙂

    • Photo: Joel Goldstein

      Joel Goldstein answered on 12 Nov 2013:

      This would be a great question for first year undergraduates!
      The Shard is 310m tall, which means that by the time you hit the ground you would be travelling close to terminal velocity, the speed at which wind resistance balances gravity. That’s about 50 m/s.
      If you land properly on a cushion, you could probably survive a deceleration of about 20 times gravity without serious injury. A quick calculation show that you would need to decelerate from 50 m/s to zero over about 15 m to achieve this. Assuming the cushions compress to about half their thickness, that requires about 30 m thickness of cushions!!
      As an experimental scientist I would note that the record for the highest deliberate free fall is only about 100 m (by a Hollywood stuntman). If you really were to jump off the Shard, you would have to make sure you didn’t bump off the building, or get blown away from the cushions by a gust of wind.

    • Photo: Tim Hollowood

      Tim Hollowood answered on 15 Nov 2013:

      I think Joel did a great analysis. Now that could be part 1 of the question. Part 2 could be

      2. Suppose they built a copy of the Shard on the moon……

    • Photo: Zachary Williamson

      Zachary Williamson answered on 15 Nov 2013:

      I think Joe already answered this one perfectly, there’s nothing more I can add!

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