Matrix:

(0,0),(0,1),(0,2),(0,3),(0,4)

(1,0),(1,1),(1,2),(1,3),(1,4)

(2,0),(2,1),(2,2),(2,3),(2,4)

(3,0),(3,1),(3,2),(3,3),(3,4)

(4,0),(4,1),(4,2),(4,3),(4,4)

force = 2
center = { x: 2, y: 2 }

[
    {
        "name": "1-1",
        "displacement": 0.5857864376269049
    },
    {
        "name": "1-2",
        "displacement": 1
    },
    {
        "name": "1-3",
        "displacement": 0.5857864376269049
    },
    {
        "name": "2-1",
        "displacement": 1
    },
    {
        "name": "2-2",
        "displacement": 2
    },
    {
        "name": "2-3",
        "displacement": 1
    },
    {
        "name": "3-1",
        "displacement": 0.5857864376269049
    },
    {
        "name": "3-2",
        "displacement": 1
    },
    {
        "name": "3-3",
        "displacement": 0.5857864376269049
    }
]

function appliedForce( m ) {
  return flatten( m )
    .filter( function ( pt ) {
      return isPointInCircle( force, center, pt );
    })
    .map( function ( pt ) {
      return {
        name: pt.name,
        d: Math.sin( 
          ( Math.PI/2 ) * 
          ( ( force - distanceBetweenPoints( pt, center ) ) / force )
        ) * 10
      }
    })
}

ES6 Version

const flatten = arr => [].concat(...arr);

const arrayOfSize = size => n => Array.from(new Array(size + 1), _ => n);

const createMatrix = size => arrayOfSize(size)(0)
    .map((_, rowIndex) => arrayOfSize(size)(0)
    .map((_, colIndex) => ({
        x: rowIndex,
        y: colIndex,
        name: `${rowIndex}-${colIndex}`
    })));

const distanceBetweenPoints = p1 => p2 => Math.sqrt( Math.pow(p1.x - p2.x, 2) + Math.pow(p1.y - p2.y, 2), 2 );

const isPointInCircle = (radius, center, point) => 
    Math.pow(point.x - center.x, 2) + Math.pow(point.y - center.y, 2) < Math.pow(radius, 2);

let m = createMatrix(5);
let force = 2;
let center = {x: 2, y: 2};

let appliedForcePoints = flatten(m)
    .filter( pt => isPointInCircle(force, center, pt) )
    .map( pt => ({ name: pt.name, displacement: force - distanceBetweenPoints(pt)(center) }) );