AS
work done =W = F.d = F d cosФ (Ф is angle between force F and displacement d) If a body/object is moving on a smooth surface (friction-less surface ) .There is no force acting on that body. F=0 so W=FdcosФ= (0)dcosФ ⇒ W=0
Now if a body is facing some amount of force but under the action of force there is no displacement covered. d=0 so W =FdcosФ= F(0)cosФ ⇒W=0
example: A person is applying a force on rigid wall but wall remains at rest there is no displacement occurs in wall.
The third term upon which work done dependent is angle between force and displacement i.e Ф. If Ф=90° then W= FdcosФ= Fdcos90⇒ W=0 ( as cos 90°=0)
A barometer is used to measure air pressure!
Scalar Quantity :-
→ These are the quantities with magnitude only . These quantities doesn't have to be mentioned with direction
eg.)=> Mass , Temprature .
Vector Quantity :-
→ These quantities are described with both Magnitude and Direction . These quantities follow special type of algebra called Vector algebra .
eg.)=> Force , Displacement
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Answer:

Explanation:
As we know that the satellite revolves around the planet then the centripetal force for the satellite is due to gravitational attraction force of the planet
So here we will have

here we have


here we have

now we can find time period as




Now the density is given as


