Question

In the 2002 film Hero, there is a scene in which Nameless (Jet Li) is fighting Sky (Donnie

Yen) in a stone courtyard. In the scene, Sky fights with a qiang (a particular type of flexible

spear), which has a length of 3 ?. Sky holds the spear at its center and swings it through an ∘

arc of 90 . In the scene, this happens in slow motion, but accounting for gravity and scaling time appropriately, the actual swing takes 0.35 ???. However, this swing does not happen at a constant speed. At the start of this motion, the spear is stationary.
a. Find the angular acceleration of the spear during this swing.

b. Find the linear (tangential) speed of the tip of the spear when it is halfway through the ∘

swing. This is at an arc of 45 , the point at which the spear would hit Nameless if he did not avoid it.

Answer 1

Here we have initial angular velocity  

The angle covered is

and time time

a) now using

so

b) let us find for

Using

So

Now.

So tangential velocity is