Solution: If the arc length of the bottom surface of 1/4 cone is 4m, the whole circumference is 4*4= 16 (m).

The radius of the cone bottom is: 16/(2π)=8/π (m).

The volume is (1/3)π*(8/π)? * 1.5 *( 1/4)≈2.5465(m3)。

The weight of this pile of corn is 785*2.5465≈2000 (kg).