Aloud speaker is tested and it is found that the sound pressure on a spherical surface (radius 3 metres and centred on the speaker) is 0.2 n/m2 air density = 1.18 kg/m3 calculate the sound pressure level spl at 3 metres and the sound power level at the source

Acompressor compresses a gas, a pump compresses a liquid. for a given pressure ratio, why does it take more work to compress a gas in a compressor than a liquid in a pump? a)- for a given pressure ratio the average specific volume for a gas is much higher than the average specific volume for a liquid. b)- there is no difference. the only difference is the amount of heat generated (not work) c)- for a given pressure ratio the average volurge for a gas is much higher than the average volume for a liquid. d)-there is no difference

How to convert a friction to decimal ?

Amachine of mass 140 kg is mounted on springs of stiffness 1.4x10° n/m and in parallel witha viscous damper of unknown damping coefficient. the machine is subject to a harmonic excitation of 200sin150t n. the phase angle is measured as 2.58 rad. what is the damping coefficient of the viscous damper?