Theory question 108
VectorsThe magnitude of a force xi + 15j is 17N. Find the: (a) possible value of x; (b) directions of the forces, correct to the nearest degree.
Show the model answer
Model answer
(a) x2 + 152 = 172, x2 = 64, x = ±8
(b) 8i + 15j: tan θ = 15/8, θ = 62° to the positive x-axis (bearing 028°)
−8i + 15j: 180° − 62° = 118° to the positive x-axis (bearing 332°)
Explanation
The magnitude of ai + bj is √(a² + b²); there are two forces, one for each value of x.