Jawaban:

7.

g = G M / r²

rA = x

rB = 5-x

g = 0  

g = gA - gB = 0

gA = gB

G4/x² = G9 / (5-x)²

4(5-x)² = 9x²

(5-x)² / x² = 9/4

(5-x) / x = 3/2

2(5-x)  = 3x

10-2x = 3x

10 = 5x

x = 2 m

jawab B

8.

ketinggian benda h  

g = G M / r²

3/4 g = G M / (h)²

3/4 G M / r² = G M / (h)²

(h)² /  r² = 4/3

h/r = 2/1,732 = 1,15

h = 1,15 r

1,15 r dihitung dari pusat bumi, bila dari permukaan bumi maka

x = h -r = 1,15 r -r = 0,15 r

jawab A

9.

g = G M / r²

gQ/gB = G M / (4r)² / G m / r²

1/4 gB/ gB = M / 16r² / m/r²

1/4 = M/16m

M = 4m

jawab D

10.

2gB/gB = G m / (4r)² / G M / r²

2 gB/ gB = M / 16r² / m/r²

2 = m/16M

m = 32M

jawab C

11.

F = G M1 M2 / r²

F = 6,67x10⁻¹¹ x 2x10²⁰ x 4x10²⁰ / (2x10⁸)²

F  = 13,34x10¹³ N

jawab A

Penjelasan: