Question

when a three is shaken it's fruit and leaves fall down . y

Answer 1

due to gravitional force from earth's core

Answer 2

HEY MATE!!

It is due to first law of Newton
The leaves are at rest, but when we suddenly shake it it tries to oppose the state of motion but as it's inertia is less it brakes and due to gravitational force towards the earth it falls towards the ground.
OR YOU CAN SAY THAT:

when a tree is shaken it's fruits fall down due to the gravitational force exerted by earth. All fruits do not fall when tree is shaken, mostly only those fruits and leaves are fallen that are ripped. It's because their tissues has become weak.