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).​

The frequency of a given region of the electromagnetic spectrum ranges from 3 × 1016 − 3 × 1019 hertz. which type of wave is found in this region? a. x-rays b. ultraviolet rays c. infrared waves d. radio waves

The graph below represents the work done by a student while running up flights of stairs. determine the student's power output after 10 seconds: 1600 j/s 8000 j/s 160 j/s 800 j/s

Afisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. it takes a time of 2.20 s for the boat to travel from its highest point to its lowest, a total distance of 0.670 m . the fisherman sees that the wave crests are spaced a horizontal distance of 5.80 m apart. (a) how much is the wavelength? (b) find the period of the wave. (c) how fast are the waves traveling? (d) what is the amplitude a of each wave?