Muscle power (MP) = an average man can lift at least half his own body weight, a fit man can do chin-ups and lift his entire weight.

We will assume Chan is fit and weighs about 70kg. To lift himself the force he is exerting to overcome gravity (approx 10 metres/second squared) is approx. 700 Newtons (mass x gravity = force).

We will assume he can apply the same force to the wooden stick. Now we need to consider a divided by b.

The radius of our knot will be approximately 3cm and the length of our wooden stick is 60cm (half b is 30cm), therefore a/b is 0.1. By calculation the force we can apply is 7000N. This is equivalent to the weight of a small car or heavy motorbike, which should be enough to bend our mild steel bar. Because the bars are reasonably long, they are also easy to bend. If the bars were shorter, Jackie may have had more of a problem escaping.

So Jackie Chan could indeed have escaped from jail, a bit of science to remember if you ever get into a pickle yourself.