Wrong gravity calculation?

Hello,

I tried following:

Adding a sphere with a sphere collider and rigidbody.

Then I was making a 60 degree ramp and put the sphere at the top of the ramp.

Now when I start the game the sphere is rolling down the ramp very slowly. Increasing the mass of the sphere doesnt affect something.

When the sphere reaches the end its falling down very fast. But why is the sphere rolling so slow?

Thanks