Who, what, why: What's the best way to catch a falling child?
A toddler who fell 10 storeys and survived after being caught by a passer-by has been making headlines around the world. But what is the best way to catch a falling child?
Zhang Fangyu, better known by her nickname Niu Niu, has become a very famous two-year-old, particularly in her native China.
The toddler has woken from a 10-day coma after falling from the window of her family's apartment in eastern Zhejiang province earlier this month. Her fall was broken by a 31-year-old woman, Wu Juping, who was knocked out by the impact and fractured her arm.
Physicists say the key to minimising injury to both child and catcher is to try and spread the energy of the impact over as much time as possible, perhaps by falling away while making the catch.
Events such as this are rare in real life, though newspapers will usually feature one or two stories a year.
In April, a mother from Nottinghamshire saved the life of a 16-month-old who fell 40ft (12m) from a hotel balcony in Florida. Helen Beard, 44, was beside the pool when she saw the toddler was about to fall. She ran and managed to catch her in her arms, before both fell to the ground.
In 2010, an 18-month-old boy survived a fall from a sixth-floor Paris apartment by bouncing off an awning and into a passing doctor's arms. Also last year, a four-year-old boy in Turkey was caught by a shopkeeper after climbing up the side of an escalator.
It is well documented that in such circumstances, a child often has better survival prospects than an adult would. This may be because children are more flexible, their bones less brittle. A smaller body mass may also mean that it is possible for a person to break their fall.
But is there anything a person can do to help them catch a falling child?
Purely hypothetically, physicist Dr Lisa Jardine-Wright has considered the main factors involved and applied the laws of physics to the situation.
Dr Jardine-Wright, of Cavendish Laboratory, Cambridge University, says the heavier the object falling, the greater the force felt by the object and the catcher.
"A 10kg bowling ball falling at the speed of the baby would force the whole person backwards at about 7mph whereas an apple would produce a barely noticeable recoil of less than 0.1mph."
The force will also be bigger if the fall is from 10 storeys rather than three as the speed will be higher by the time the catch is made.
"Whatever is receiving the collision, whether it is a brick wall or a mattress or a car or someone catching a baby, if the energy of the collision can be transferred over time rather than instantaneously, then the impact is reduced."
She says you could compare the falling child scenario with football goalkeepers and cricket fielders, who rather than remain rigid and upright, often fall as they catch the ball.
"If you fell as you caught the baby that might help as you are reducing the impact of the catch. You want to be able to fall safely, so grass and soil will give a little bit more than say concrete.
"The arms are going to take some of the force, so it would help if they were relaxed and loose."
Using the analogy of stunt men in action films falling through canopies before falling to the ground, she added: "If you can slow the object down however you do it, then that will help.
"If you were able to put something above the ground, some kind of material that would stretch rather than break, some of the energy will be absorbed in the material and the baby would be brought to a standstill gently."
From the laboratory to reality, a passer-by confronted with a falling child would have little time to weigh up the situation.
Andy Kettle, operational director at the Fire Service College, says there is nothing anyone can do in such "freak" accidents.
He says it is not part of their training as there would never be enough time to get to the scene with a trampoline or mattress.
"There are no techniques or equipment that we could put in place," he says.
"It happens so quickly and it is such an unexpected event, the person falling would have little or no control over their own body and for the people on the ground, if it's a small child, it is a hit or miss attempt to soften the fall.
"It only takes seconds for people to fall fairly big distances. There will be very little time to think about taking any practical steps."