Equations of Motion

A boat is sent across a river with a velocity of 8 km h^-1. If the resultant velocity of the boat is 10 km h^-1, then the velocity of the river is:

A 120 m long train is moving with a speed of 20 m/s. A train B moving with 30 m/s in the opposite direction and 130 m long crosses the first train in a time:

The width of a river is 1 km. The velocity of a boat is 5 km/hr. The boat covers the width of the river in the shortest time of 15 min. Then the velocity of the river stream is:

The width of a river is 1 km. The velocity of a boat is 5 km/hr. The boat covers the width of the river in the shortest time of 15 min. Then the velocity of the river stream is:

Two particles A and B are connected by a rigid rod AB. The rod slides along perpendicular rails as shown. The velocity of A to the left is 10 m/s. What is the velocity of B when angle α = 60°?

A person aiming to reach exactly the opposite point on the bank of a stream is swimming with a speed of 0.5 m/s at an angle of 120° with the direction of flow of water. The speed of water in the stream is:

The speed of a swimmer in still water is 20 m/s. The speed of river water is 10 m/s and is flowing due east. If he is standing on the south bank and wishes to cross the river along the shortest path, the angle at which he should make his strokes with respect to north is given by:

One day on a spacecraft corresponds to 2 days on the Earth. The speed of the spacecraft relative to the Earth is: