The sp² hybridized carbon atoms of alkenes and benzene rings are and absorb . ¹³ c nmr absorptions typically occur over the range of ppm. a triplet is an nmr single that is split into three peaks having a relative area of , caused by nearby nonequivalent protons. an upfield shift means a signal is shifted to the in the spectrum to chemical shifts. electronegative elements like halogens, nitrogen, and oxygen shift absorptions . the proton’s is determined by shielding and deshielding effects. a doublet is an nmr signal that is split into two peaks of area, caused by nearby nonequivalent proton. a downfield shift means a signal is shifted to the in the spectrum to chemical shifts on the δ scale. the sp³ hybridized carbon atoms of alkyl groups are and absorb .

Tom is having a problem with his washing machine. he notices that the machine vibrates violently at a frequency of 1500 rpm due to an unknown rotating unbalance. the machine is mounted on 4 springs each having a stiffness of 10 kn/m. tom wishes to add an undamped vibration absorber attached by a spring under the machine the machine working frequency ranges between 800 rpm to 2000 rpm and its total mass while loaded is assumed to be 80 kg a) what should be the mass of the absorber added to the machine so that the natural frequency falls outside the working range? b) after a first trial of an absorber using a mass of 35 kg, the amplitude of the oscillation was found to be 10 cm. what is the value of the rotating unbalance? c) using me-3.5 kg.m, find the optimal absorber (by minimizing its mass). what would be the amplitude of the oscillation of the absorber?