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Class 10 Class 12
A person standing on a road has to hold his umbrella at 300 with the vertical to keep the rain away. He throws the umbrella and starts running at 10 m/s. He finds that raindrops are hitting his head vertically. Find the speed of raindrops with respect to,

b) the moving person.

When a person is at rest with respect to ground, the rain is coming to him at an angle 30o with the vertical, i.e., along OB.

As the person moves along OA with velocity 10 m/s, the relative velocity of rain w.r.t person is along OC as shown in fig. below.

Here, o

Therefore, velocity of rain w.r.t ground =

Velocity of person w.r.t. ground =

Velocity of rain w.r.t person =

a)

b)

In

= 10/ (1/) = 10

Therefore, velocity of train w.r.t person = 10 m/s

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Give three examples of scalar quantities.

Mass, temperature and energy
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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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Give three examples of vector quantities.

Force, impulse and momentum.
865 Views

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.
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