Question

15. If the radius of the Earth is halved and the mass is doubled, then what will be the value of 'g? (g=9.8 m/s2) (A) 78.4 m/s2 (B) 48.85 m/s2 (C) 9.8 m/s2 (D) 98 m/s2​

Answer 1

Answer:

a) 78.4 m\s2

Explanation:

2*4 gm\r2

8*9.8=78.4

hence, g =78.4m\s2

Answer 2

Given,

Radius of the earth is halved,

mass is doubled

To Find,

The value of g.

Solution,

We know, g=9.8m/s2

There is a formula ,

g=GM/R²

As new mass is double of initial mass,

So, M'=2M

New radius is half of initial one

So, R'=R/2

So if we put the values the formula will be,

g'=G(2M)/(R²/4)

  =2×4×GM/R2

  =8×9.8(∵g=GM/R²=9.8)

  =78.4m/s²

Hence, the value of 'g' will be 78.4m/s²(Option A).