Assume you have a circular 0.1m diameter dual frequency transducer 50/200 khz operating with peak output power of 4000w peak (500w rms) in shallow 60ft water assuming a back scattering coefficient of -15db, absorption coefficient of-3db and a fixed incident (look) angle of 20 degrees. assume vs = 1,495.5 m. s1, the source level of 145db, the noise level of 4db, and the ideal sea surface conditions. compute the return echo power (in db) for the a) low frequency beam b) high frequency beam, and c) compute the pulse length for a pulse rate of 0.5milliseconds for the high frequency beam [hint: pulse length is defined as lp = nc'x where the number of cycles nc = r'f for the pulse rate r ] where i ix a and a=2-r2

Which device uses ac current to operate?

Air is held within a frictionless piston-cylinder container, which is oriented vertically. the mass of the piston is 0.45 kg and the cross-sectional area is 0.0030 m2. initially (state 1) the pressure of the gas is sufficient to support the weight of the piston as well as the force exerted by the atmospheric pressure ( 101.32 kpa). the volume occupied by the air within the cylinder in state 1 is 1.00 liter. one end of a spring (with spring constant k = 1000 n/m) is attached to the top of the piston, while the other end of the spring is attached to a stage that can move vertically. initially the spring is undeflected and therefore exerts no force. then the stage is then moved quasistatically downward a distance of 10.0 cm, at which point the system reaches state 2. the piston-cylinder is not insulated; rather it remains in diathermal contact with the surroundings, which are at a constant temperature of 300 k. what is the change of pressure within the container?

If the force applied to an object remains constant, is more power needed for the object to move faster ? explain