3. (12) (a) Sonar is used for commercial fishing to detect schools of fish which have internal air sacks. Assume that the sonar is generated with a power of 0.18 W at 50 kHz that spreads in a 35o cone as it propagates into water. If 18% of the sound energy reaching the school of fish is reflected and scattered uniformly, calculate the power density reaching the school of fish, and the power density reflected from the fish at 55 meters. (Attenuation in water at 50 kHz is 13 dB/km.) (3) (b) What would happen to the power density of the sonar reflected from the fish at 55 m, if the frequency of the sound waves were increased by 10%

When temperature of a substance increases, of its particles increase resulting in more between particles. real world applications of thermal expansion absolute zero (-273 degrees c) is the lowest possible temperature on the kelvin scale. it is a measure of where a substance has no kinetic energy. heat is a process of the . energy flows spontaneously from a object to a until equilibrium is reached. heat is measured in heat is transferred throughis a method of heat transfer that occurs between particles of matter that are in direct contact with each other. are poor conductors that impede / reduce the rate of heat transfer. is a method of heat transfer that occurs in fluids (non-solids) by means of currents. real world application of convectiona method of heat transfer through electromagnetic waves. when energy moves from one object to another inside a closed system, no energy is or in the system in the transaction. systems will spontaneously move to a state of organized energy or high disorder over time called

How does an observation about an object differ from an inference about that object

Abeam of electrons moves at right angles to a magnetic field of 4.5 × 10-2 tesla. if the electrons have a velocity of 6.5 × 106 meters/second, what is the force acting on the electrons? the value of q = -1.6 × 10-19 coulombs.