Question

A light house which faces the north , throws light beam in the shape of a fan from north-east to north-west in the sky. On a ship a man that is going to west looks the light for the first time. When he is 8km distance from the light house and continuously looks it for 15√2 minutes, then find out the speed of the ship in km/h.​

Answer 1

Given:-

• distance between man and light house = 8km.

To Find:-

• the speed of the ship in km/h.

step-by-step solution:-

→ O is a light house which faces north. when ship reaches pint A then it looks light, where OA = 8 km.

→When the ship reaches at point B after 15√2 minutes, then it happens to see the light.

So, OB = OA = 8 km

From right angled ΔBCO.

⟶ Sin 45° = BC/BO = 1/√2

⟶ BC/8 = 1/√2

⟶ BC = 8/√2 = 4√2

So,

⟶ AB = 2BC = 4 × 2√2

⟶ 8√2km.

Speed = Distance/time

⟶ 8√2/15√2 km/min

⟶ 8/15 × 60 km/h

⟶ 32km/h

Hence, speed of aeroplane = 30 km/h.