Question

a ship A , steaming in a direction 030° with a steady 12 km/h, sight a ship B. The velocity of B relative to A is 10km/h in a direction of 270°. find the magnitude and direction of the velocitybof ship B. [11km\h;339°]​

Answer 1

Answer: 11 km/h at 339° compass

Explanation:

A sees B moving south at 0 km/h

A is moving north at 12cos30 = 10.392 km/h

Therefore B must be moving north at 10.392 k/h

A is moving east at 12sin30 = 6 km/h

B appears to be moving west at 10 km/h

Therefore B must be moving west at 10 - 6 = 4 km/h

B is moving v = √(4² + 10.392²) = 11.135... 11 km/h

θ = arctan( -4 / 10.392) = -21.05 = 339°