Table of Contents
How do you cross the river in the shortest time?
To cross a river by the shortest path, man’s velocity (relative to the ground) is perpendicular to the flow. To cross a river in minimum time, man’s speed relative to the water should be perpendicular to the river flow.
In what direction should a swimmer swim across a river so as to cross it along the shortest path What time is taken by him to swim across?
Explanation: Taking d to be the width of the river and also the the shortest distance covered by the swimmer. If the swimmer makes an angle θ with the upstream, then angle (90-θ) will be normal to the stream. Thus, shortest time taken will be the own distance i.e t=d/v.
When a boat tends to cross a river along the shortest path?
When he crosses a river with shortest time one component of boat velocity is opposite to velocity of water and other component is perpendicular to velocity of water. here shortest path=x and time=12.5 min =750 sec.
How do you find the time on a river boat problem?
The time taken by the boat t=d/|→vb|=30/5=6hr t = d / | v → b | = 30 / 5 = 6 h r . In upstream motion, the speed of the boat is equal to the difference of the speed of boat in still water and the speed of river water.
What is minimum drift?
Minimum Drift. Problem: A boat moves relative to water with a velocity 10 km/hr. The velocity of river flow is 5 km/hr. Solution: The drift is zero if boat reaches directly opposite point.
How does river velocity affect time to cross the river?
The river velocity, being perpendicular to the crossways motion of the boat, does not affect the time to cross the river. Any alteration in the river velocity will have no affect upon the time to cross the river.
What is drift in River?
Answer: Due to speed of water flow in river, a person either swimming or floating stationary in the river experiences a pushing force along the flow direction. This is known as drift.
How should a swimmer cross the river in the shortest distance?
To cross the river in shortest distance, a swimmer should swim making an angle θθ with the upstream. What is the ratio of the time taken to swim across in the shortest time to that in swimming across over shortest distance. [Assume that the speed of swimmer in still water is greater than the speed of river flow]
What happens when a person wants to cross a river?
As a result of the river velocity the person will reach a point say C from A. (drawn the current). When a person wants to cross a river flowing at the rate of 2m/s in the least possible time, he undergoes a drift of 20m along the flow of the river. The width of the river is 100m.
How do you calculate the time taken to cross a river?
Time taken to cross river, t 1 = d/v sr For shortest distance case- Time taken to cross river, t 2 = d/v sr cos θ where θ is the angle made by swimmer w.r.t the direction normal to the direction of flow of river.
What is the speed at which a man can swim?
A man can swim in still water with a speed of 2 ms^-1 . If he wants to cross a river of water current speed √ (3) ms^-1 along shortest possible path, then in which direction should he swim?