The two speakers at S1 and S2 are adjusted so that the observer at O hears an intensity of 6 W/m2 when either S1 or S2 is sounded alone. The speakers are driven in phase (at the speakers) with various frequencies of sound. The distance between the two speakers is L = 4 m and distance between S1 and the observer is also L = 4 m. Assume that the speed of sound is 335 m/s. 1)What is δ, the difference in the path lengths that the sound waves from S1 and S2 must travel in order to reach the observer?

the chart show the masses and velocities of two colliding objects that stick together after a collision.

according to the law of conservation of momentum, the momentum of the object after the collision is  

answer

1,500

kg • m/s.

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia