Question

Car A, traveling south at 30 feet per second, is 400 feet due north of an intersection. Car B, traveling west at 40 feet per second, is 300 feet due east of the same intersection. At this point in time how fast, in feet per second, is the distance between Car A and Car B changing?

a) 42

b)44

c)46

d)48

Answer 1

ZT o intersection poing VAD dy = -30 ft/sec VB = d = -40 ft Isec 9 dot С педајve siyo be с аме охуев - length of both x and y are decreasing). Now, for x = 300 and y= 400, z = (x)2+(y)? = $(300)2 +(400) 2 + z = 500 ft 77 als on dit z = 2? ty? = dlz) = (22) + (y?) - 22% z = 2x du + 2y x 2 1 2 dt Hence, at n= 300, y = you and z =500 d2 = 300 × (-40) + Y008 (-30) Ѕбъ = - 48 Hence, distance between car A and Car B IS is decreasing at 48 ft/sec