Why is a large amount of energy released during fission of uranium ( U -235) ?

In a certain star, three alpha particles undergo fusion in a single reaction to form 6 12 ​ C nucleus. Calculate the energy released in this reaction in MeV. Given: m( 2 4 ​ He)=4.002604 u and m( 6 12 ​ C)=12.000000 u.

Explain, why is it difficult for a fireman to hold a hose, which ejects large amounts of water at a high velocity.