Question

it is much easier to burst and inflated balloon with a needle then directly with the finger

Answer 1

Hi friend!

The reason is the needle is pointed.

Scientific reason:
The surface area of the pointed end of the needle is small. So, the pressure is more on the balloon due to which the bursts.

That's it, my friend. Hope you found my answer useful .

Answer 2

The tip of the needle is sharp so that due to its sharp tip, the needle may put force on very small area of balloon , producing a large pressure sufficient to pierce the balloon where as, if we use finger to burst balloon, the surface area of it is more and blunt . Hence less pressure will act on balloon which is not sufficient to burst it.