What is the best description of sound waves?

a. a source vibrates up and down, causing air molecules to move up and down perpendicular to the direction the wave is transmitted
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b. a source vibrates back and forth, causing air molecules to move back and forth in the same direction that the wave is transmitted.

c. a source vibrates up and down and back and forth, causing air molecules to move in a circular motion as the wave is transmitted.

d. a source ejects a ring of high-velocity air molecules that travel from the source to a listener.

Two identical 82 mg dust particles very far apart (pee 0) are moving directly toward each other at a speed of 3698 m/s. the charge on each is-719 ? c. determine how close they will get to each other. let k = 9x109 n-m2/c2 & ignore gravity.

The pressure proportional to the area a- inversely b- directly c- increase d-decrease

Aperson gives a shopping cart an initial push along a horizontal floor to get it moving, and then lets go. the cart travels forward along the floor, gradually slowing as it moves. consider the horizontal force(s) on the cart while it is moving forward and slowing. which of the following statements is correct? (a) both a forward and a backward force are acting on the cart, but the forward force is larger. (b) only a forward force is acting which diminishes with time. (c) both a forward and a backward force are acting on the cart, but the backward force is larger. (d) only a backward force is acting, no forward force.