B. |y| = 1.6
A sketch of the vector is attached to this response.
As shown, the vector lies on the second quadrant and its horizontal and vertical components are given by x and y respectively.
Where;
|x| = v cos θ -----------------(i)
|y| = v sin θ -----------------(ii)
and
v = magnitude of the vector = 2.5km/hr
θ = angle that the vector makes with the +x axis = 90° + 50° = 140°
To get the magnitude of the vector's vertical component
Substitute these values into equation(ii) as follows;
|y| = 2.5 sin 140°
|y| = 2.5 x 0.6428
|y| = 1.607
|y| ≅ 1.6 km/hr
Therefore, the vertical component of the vector has a magnitude of 1.6 km/hr.