A120 kg machine is mounted on a spring of stiffness 7.68x10 n/m with no viscous damping. during operation the machine develops a harmonic force at a frequency of 100 rad/s. is it better to use an accelerometer of natural frequency 600 rad/s or a seismometer of natural frequency 600 rad/s to measure the vibrations? explain.

Awall of 0.5m thickness is to be constructed from a material which has average thermal conductivity of 1.4 w/mk. the wall is to be insulated with a material having an average thermal conductivity of 0.35 w/mk so that heat loss per square meter shall not exceed 1450 w. assume inner wall surface temperature of 1200°c and outer surface temperature of the insulation to be 15°c. calculate the thickness of insulation required.