Question 4: Figure 1 shows a block foundation of mass 200 kg supported by two springs of stiffness k = 60 kN/m and a viscous vibration damper with damping coefficient c = 1000 Nm/s. The foundation carries a 40 kg rotating machine which induced 50 N harmonic forced. The foundation block was observed to vibrate badly at frequency of 204 rpm. Explain why the foundation block experienced high vibration phenomena and suggest a solution to reduce half of its vibration amplitude.

As illustrated in the figure below, the bedplate of an experimental diesel engine is supported on four springs to isolate the vibrations from the test frame. The effective weight of the diesel engine and bedplate is 43kg and the stiffness of each of the four springs is 250 kN/m. Using a simplified approach - by applying Newton's Second Law assuming a single degree of freedom system and ignoring damping - what rotational engine speed is best avoided? Bedplate Test engine Supporting springs Figure: Sketch of a test engine mounting arrangement Give your answer in rad/s to 1 decimal place.

answer ASAP would be appreciated