A German scientist joined two hollow metallic hemispheres and created a vacuum inside them by pumping the whole air out. Then he employed eight horses on each hemisphere to pull them apart but the horses failed to do so. Give reason for this.

Explanation

There being no air inside, there was no opposition to the outside atmospheric pressure acting over the whole surface of hemispheres with the result that this outside pressure pressed the hemispheres very very hard and did not allow them to be separated.