A beam is made out of a material with properties given below. Also given
are the properties of the beam's cross-section relevant for this
problem (N.A. = neutral axis).

Cross-section :

Central moment of inertia :

= 6 cm^{4}

Distance from N.A. to top of beam :

a = 1.0 cm

Distance from N.A. to bottom of beam :

b = 1.4 cm

Stress limits for material :
Tension : 60 MPa
Compression : 120 MPa

Determine the largest positive bending moment (compression at top) and
the largest negative bending moment (tension at top) the beam can be
exposed to.