Question 18(Multiple Choice Worth 2 points) Which statement best describes an isolated system?
O Energy flow into and out of the system but matter is contained.
O Energy is contained within the system and matter is exchanged.
ONeither energy nor matter are exchanged with the surroundings.
There is no energy or matter that exists inside an isolated system.

Wo audio speakers are placed on a vertical rail. speaker a is placed at head-level while speaker b is place at some variable height, \delta yδy, above speaker a. both speakers receive simultaneous input from a sine-wave generator so the speakers each produce a pure sinusoidal sound wave with a wavelength of 0.531 meters. calculate the lowest height that speaker b can be placed above speaker a to produce a minimum of sound heard by person standing \delta x = 7.86δx=7.86 meters directly in front of speaker a.

Aspring is used to stop a 50-kg package which is moving down a 20º incline. the spring has a constant k = 30 kn/m and is held by cables so that it is initially compressed 50 mm. knowing that the velocity of the package is 2 m/s when it is 8 m from the spring and neglecting friction, determine the maximum additional deformation of the spring in bringing the package to rest.

Describe how the motion of a spring being pushed forward and backward is similar to the motion of air particles in a sound wave.