Using Laplace transforms, solve $${a \over {{s^2} - {a^2}}}\,\,\left( {{d^2}y/d{t^2}} \right) + 4y = 12t\,\,$$
given that $$y=0$$ and $$dy/dt=9$$ at $$t=0$$

In natural water, hardness is mainly caused by

During a 6-hour storm the rainfall intensity was 0.8 cm/hr on a catchment of area 8.6 km². The measured runoff volume during this period was 2,56,000 m³. The total rainfall was lost due to infiltration, evaporation and transpiration in cm/hr is

Modulus of elasticity of M25 grade concrete in MPa is