GRAVITATION

11 )

One can easily find “Weight of the earth” by calculating the mass of earth using the formula (in usual notation)

Select Correct option from the following options

(A) (g/G)Re (B) (g/G) Re²

View Solution

Answer :

Let Me – mass of earth

Re – radius of earth

m – mass of a body.

then

F = [(GMem) / (Re²)]

mg = [(G ∙ Me∙ m) / (Re²)]

g = [(G ∙ Me) / (Re²)]

Me = (g/G)Re²

12 )

Which of the following statement about the gravitational constant is true

It is a force

It has no unit

It has same value in all system of unit

It depends on the value of the masses.

View Solution

Answer :

Gravitation constant is a force

13 )

Two point masses A and B having masses in the ratio 4 : 3 are separated by a distance of lm. When another point mass c of mass M is placed in between A and B the forces A and C is (1 / 3rd) of the force between B and C, Then the distance C from A is = ………. m

(2/3)

1/3

1/4

2/7

View Solution

Answer :

Given (m_A / m_B) = 4/3

d(AB) = 1m

Let point C be at distance x from A.

F_AC = [(G ∙ m_A ∙ m) / x²]

and

F_BC = [(m_B ∙ m ∙ G) / (1 – x)²]---------- F = [(G ∙ m₁ ∙ m₂) / r²]

Given : F_AC = (1/3)F_BC

hence

[(G ∙ m_A ∙ m) / x²] = (1/3) ∙ [(G m_B ∙ m) / (1 – x)²]

3 ∙ (m_A / m_B) = [x² / (1 – x²)]

3 × (4/3) = [x² / (1 – x)²]

hence 2 = [x / (1 – x)]

hence 2 – 2x = x

x = (2/3)

14 )

The gravitational force between two point masses m₁ and m₂ and separation r is given by F = G[(m₁m₂) / r²] The constant K …….

Depends on system of units only.

Depends on medium between masses only.

Depends on both (a) and (b)

Is independent of both (a) and (b)

View Solution

Answer :

Constant G depends on system of units only.

15 )

As we go from the equator to the poles, the value of g ………

Remains constant

Decreases

Increases

Decreases upto latitude of 45°

View Solution

Answer :

g is minimum at equator and maximum at poles hence g increases from equator to poles

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