Chapter 4, Problem 4.21P

! Required information Two chloride ions and two sodium ions are in water, the "effective charge" on the chloride ions (CI¯) is −2.00 × 10-21 C and that of the sodium ions (Na+) is +2.00 x 10-21 C. (The effective charge is a way to account for the partial shielding due to nearby water molecules.) Assume that all four ions are coplanar. CT Na+ Na+ 30.0° 45.0% с сг L. where a = 0.300 nm, b = 0.710 nm, and c = 0.620 nm. What is the direction of electric force on the chloride ion in the lower right-hand corner in the diagram? Enter the angle in degrees where positive indicates above the negative x-axis and negative indicates below the positive x-axis.

A pendulum has a 0.4-m-long cord and is given a tangential velocity of 0.2 m/s toward the vertical from a position 0 = 0.3 rad. Part A Determine the equation which describes the angular motion. Express your answer in terms of the variable t. Express coefficients in radians to three significant figures. ΜΕ ΑΣΦ vec (t)=0.3 cos (4.95t) + 0.101 sin (4.95t) Submit Previous Answers Request Answer × Incorrect; Try Again; 6 attempts remaining

Part A ■Review The uniform 150-lb stone (rectangular block) is being turned over on its side by pulling the vertical cable slowly upward until the stone begins to tip. (Figure 1) If it then falls freely (T = 0) from an essentially balanced at-rest position, determine the speed at which the corner A strikes the pad at B. The stone does not slip at its corner C as it falls. Suppose that height of the stone is L = 1.2 ft. Express your answer to three significant figures and include the appropriate units. ? ft VA 10.76 S Submit Previous Answers Request Answer × Incorrect; Try Again; 6 attempts remaining