Boats and Streams Tips and Tricks for Government Exams

Introduction

• Downstream: If the boat is moving in the direction of the stream.
• Upstream: If the boat is moving in the direction opposite to the direction of the stream.

Assume the speed of the boat in still water as: ‘b’ kilometres per hour (kmph).
Take the speed of the stream as:  ‘s’ kmph.
Hence Aggregate Downstream Speed = b + s kmph. (Boat is moving with the steam of water).
Upstream Net Speed = b - s km/hr. (Boat is moving against the direction of the stream).

Theory

• Stream – The moving water in a river is called a stream. 
• Upstream – If the boat is flowing in the opposite direction to the stream, it is called upstream. In this case, the net speed of the boat is called the upstream speed
• Downstream – If the boat is flowing along the direction of the stream, it is called downstream. In this case, the net speed of the boat is called downstream speed
• Still Water – Under this circumstance the water is considered to be stationary and the speed of the water is zero

Formula's

• Upstream: (u−v) km/hr
• Downstream: (u+v)Km/hr
• Speed of Boat in Still Water: ½ (Downstream Speed + Upstream Speed)
• Speed of Stream: ½ (Downstream Speed – Upstream Speed)
• Average Speed of Boat: {(Upstream Speed × Downstream Speed) / Boat’s Speed in Still Water}
• Speed of boat or swimmer in still water: 1/2 (Downstream Speed + Upstream Speed)

Solved Examples