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Class 10 Class 12

A river d km wide is flowing at the rate  A swimmer which can swim with velocity  relative to water wants to cross the river straight across. Find how long will he take to cross the river?

The path AB is the shortest path to cross the river.

To cross the river straight across along path AB, the resultant velocity of swimmer and the water flow should be along AB i.e. perpendicular to the direction of water flow.

To meet this condition, let the swimmer start swimming upstream at angle 0 with AB.

Therefore,

Now,

Time taken by the swimmer to cross the river is,

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Give three examples of scalar quantities.

Mass, temperature and energy
769 Views

What are the basic characteristics that a quantity must possess so that it may be a vector quantity?

A quantity must possess the direction and must follow the vector axioms. Any quantity that follows the vector axioms are classified as vectors.

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What is a vector quantity?

A physical quantity that requires direction along with magnitude, for its complete specification is called a vector quantity.
835 Views

What is a scalar quantity?

A physical quantity that requires only magnitude for its complete specification is called a scalar quantity.
1212 Views

Give three examples of vector quantities.

Force, impulse and momentum.
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