A prestressed concrete beam of size 400 × 800 is prestressed by using 10 tendons of 12 mm diameter each having prestressing stress of 100 MPa located at a distance of 300 mm from the soffit of the beam. The beam is subjected to a Live load of 30 kN/m and has an effective span of 6 m. Calculate the factor of safety against cracking considering the loss in prestressing is 20% and neglect the self-weight of the beam. Use M50.