1.Mention 4 effects of noise. 2.Calculate the absorptivity of a plastic surface that reflects two-thirds of sound energy incident on it. 3.A cylindrical block of concrete is 300mm long and has a circular cross section of 100mm diameter. It experiences a reduction of 0.2% in length under a load of 67kN. i. What is the type and numerical value of of the stress (show working). ii. What is the axial strain (show working). iii. Calculate the modulus of elasticity (show working).​