A certain vector in the xy-plane has an x-component of 4 m and a y-component of 10 m. It is then rotated in the xy-plane so that its x-component is doubled. Then its new y-component is (approximately)

Options

A. (a) 20 m
B. (b) 7.2 m
C. (c ) 5.0 m
D. (d) 4.5 m

Answer

(b)

Explanation

Given x component - 4 m and y component - 10 m
`z = 4i + 10j`
`|z| = sqrt((4)^(2)+(10)^(2)) = sqrt(116) m`
`rArr n^(2) = 52`
`:.`n = 7.2 m