Question

When in going east at 10 km/h a train moving with constant velocity appears to be moving exactly north - east. when my velocity is increased to 30 km/h east it appears to be moving north

What is the velocity of train along north (in Kmph)?

• A. 30 km/h
• B. 20 km/h
• C. 50 km/h
• D. 10 km/h

Answer 1

The correct option is D 10 km/h

We know that,

The train appears to be moving exactly toward north east when speed of observer is $10km/h$towards east.

Now, the angle made by train with the direction of east is ${45}^0$

Therefore, the speed of train along

the direction of north

$v_n=v\sin {45}^0$

$v_n=10\times 1$

$v_n=10km/h$

hence, the speed of train along north is $10km/h$