Question

if we throw a ball up after sometime its comes down why

Answer 1

Here is your answer friend,
It comes down because of the gravitational force of the earth.
Gravitational force attract things to the ground.
Hope it's useful and helpful!!!
@#shakti37

Answer 2

When we throw a ball up it comes down but not every time, if you know something bout the escape velocity (which is 11.2km/sec for earth), if you throw something with this velocity the object will never come back Coz it will escape from Earth’s orbit and moves in spae
Now coming to point,.
If the object comes down then the only reason of this is gravity, gravity pulls it towards the ground.