# What condition is satisfied if the swimmer desires to swim minimum distance to cross the river?

To cross the river in shortest distance, a swimmer should swim making angle θ with the upstream.

## How do you find the shortest time to cross the river?

Complete step by step answer: drift=T×vR or vR=DriftTime, here drift=120m and time = 10 min=600 s. 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.

## What happens if the river direction time is too large?

EXPLANATION: Reverberation is the time taken for the sound to fall below the minimum audibility measured from the instant when the source stopped sounding. Therefore if the reverberation time becomes too large it produces an echo. So option 2 is correct.

## How do you calculate the drift on a river boat problem?

The boat cannot cross the river to an exactly opposite point. In this case, the drift is minimum if →vb=→vb/w+→vw v → b = v → b / w + v → w is perpendicular to →vb/w v → b / w . The angle made by →vb/w v → b / w with →vw v → w is given by θ=cos−1−vb/wvw=cos−1−12=150degree.

## How fast is the river flowing physics?

The speed of a river varies from close to 0 m/s to 3.1 m/s (7 mph). Factors that affect the speed of a river include the slope gradient, the roughness of the channel, and tides. Rivers tend to flow from a higher elevation to a lower elevation.

## Why is it difficult to cross fast flowing river using a boat?

The river moves downstream parallel to the banks of the river. As such, there is no way that the current is capable of assisting a boat in crossing a river.

## How do you calculate minimum drift?

to find minimum D, we differentiate and then equate to 0 dDdt=0ut−vsin(x)t=D. If we have the velocity of the boat and the velocity of the river, then we can find the angle for which drift is minimum for that particular velocity of boat using the above relation.

## Does water flow faster in a wide river?

Generally a narrower, more circular river channel allows faster flow of water. Broader flat channels tend to slow a river down.

## Why do rivers flow faster than water flowing into a well?

This means that less of the water is in contact with the bed of the river and the mouth so there is less energy used to overcome friction. Hence rivers flow progressively faster on their journey downstream. Width and depth increases as more water is added from tributaries.

## Do rivers ever go in reverse?

But why is Chicago where it is? It all has to do with an ancient Indian canoe portage—and the only river in America that flows backwards.

## What is drift in river problems?

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.

## What is drift in relative velocity?

For observer 1 the velocity of the river will be VM=VMR+VR. Therefore the swimmer will appear to move at an angle θ’ with the river flow. 1. Drift. It is defined as the displacement of the man in the direction of the river flow.

## What is the speed of the boat relative to the water?

The velocity vBW of the boat relative to the water is the velocity measured by an observer who, for instance, is floating on an inner tube and drifting downstream with the current. When the engine is turned off, the boat also drifts downstream with the current, and vBW is zero.

## What affects the velocity of a river?

The velocity of a river is determined by many factors, including the shape of its channel, the gradient of the slope that the river moves along, the volume of water that the river carries and the amount of friction caused by rough edges within the riverbed.

## Why does the speed of a river decrease?

Answer: The base level of river is almost same as the sea level as river enters plains and approach sea. As there is not much difference in height, water speed reduces. At plains, rivers move in meanders instead of straight and this can reduce the speed as well.

## Which direction should the boat point in order to reach the other side of the river in the least amount of time?

Which direction should the boat point in order to reach the other side of the river in the least amount of time? flow of the river and take the most direct path across the stream. It will be the shortest distance and therefore the shortest amount of time.

## What is the resultant velocity of the boat?

The resultant velocity will this stretch from the tail of the boat velocity (if drawn first) to the arrowhead of the river velocity. This resultant velocity will be a vector directed south and east (or south and west, depending on the direction of the river velocity.)

## What is the angle for minimum drift?

Note: It is worth noting down here that, the boat can also move with other angles also, but to satisfy the need to the question that there should be minimum drift to reach at directly opposite bank of the river we need to move the boat at an angle of 120 degrees with the horizontal.

## What is velocity in still water?

Velocity of boat in still water is 13m/s.

## What is circular motion formula?

The instantaneous acceleration in a uniform circular motion is given by. a = v2/R. v is the velocity of the object. R is the radius of the circle. The direction is perpendicular to velocity and directed inwards along the radius.

## At what angle with river flow he should swim to travel minimum distance?

He should travel at an angle x with respect to the direction perpendicular to the river’s flow, towards the direction opposite to river’s flow. Therefore, for minimum distance, vsinx=u. Hence, the velocity of the swimmer would be equal to vcosx=√v2−u2.

## Why does the lower part of an individual appear so much different in size from the upper part when they are in swimming pool?

Why does the lower part of the child appear so much different in size from the upper part? The light rays that travel through water and then into air are refracted. The light rays that travel through water and then into air are enlarged.

## What do we call the person who is present at the swimming pool and safeguards swimmers?

A lifeguard is a rescuer who supervises the safety and rescue of swimmers, surfers, and other water sports participants such as in a swimming pool, water park, beach, spa, river and lake.