I'm sure you have noticed that a shuttlecock
(a.k.a. birdie) is much heavier on the bottom than
it is by the feathers. The way the weight is
placed makes a big difference in how we perceive
its motion, but the same physical laws apply. When
you swing a badminton racket and meet the birdie,
it is essentially the same as when you throw a
ball at a wall: it bounces back (unless the ball
is flat!) In this case, the birdie is the "ball"
and the strings on your racket are the "wall."
Newton's Third Law tells us that objects that
interact (like a racket and shuttlecock) force
each other equally and oppositely. The force from
a hit comes from the change in velocity as well as
the time it takes to make that change. In this
case, the birdie is changing velocity. Remember
that velocity has a speed (how fast?) and a
direction (where?) part to it.
The birdie changes its position in air as a
result of you putting a force on it through the
racket. With a very fast camera and some
estimations, we can figure out about what kind of
force is put on a birdie.
Using this website as a guide: click here to see,
please), I will estimate a few things:
Type of shot: Forehand smash (the awesome
Incoming velocity: -15 meters / second
Outgoing velocity: 75 meters / second
(remember it's now going in the opposite
This means the change in velocity is (final -
initial) = 100 meters/sec
Impact time: 0.004 seconds
Shuttlecock mass: 5 grams = 0.005 kilograms
Force is equal to mass*(change in velocity) /
So, the force on a shuttlecock in a
professional game is 125 Newtons. This is about
the force of 30 pounds (three bowling balls),
which doesn't seem like much, but remember how
small the birdie is!
The acceleration on the shuttlecock is very large.
Acceleration is equal to (change in velocity) /
(impact time) = 25,000 meters/(sec2)
over 2500 times the acceleration of gravity (often
noted as 2500 G, just meaning 2500 times Gravity).
For comparison, NASA's retired space shuttle
reached 3 G's during liftoff. A scientist named
John Stapp holds the record for maximum horizontal
acceleration tolerated by a human:
He had vision problems for the rest of his life as
a result of this experiment.
here to read about It's clear that a birdie
can tolerate higher accelerations than a human.
Hope you have a better appreciation for how
tough that little birdie is!
Thanks for the question! Here's a cool video of
some badminton shots:
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