Question

A body weighs 90kg on the surface of the earth. If the mass
of Mars is - th that of the earth and radius is half that of
the earth, the weight of the body on Mars in kg-wt is:
(1) 20
(2) 40
(3) 60
(4) 90​

Answer 1

hi,mate

ur answer

2) 40 is ur correct answer.

Answer 2

Answer:

<b> Acceleration due to gravity is calculated as

a = GM / R²

Where M = Mass of Planet and R is radius of Planet.

For earth

9.8 = GM / R² …………(1)

For Mars

g = G × (M/9) / (R / 2)²

g = (4/9) × GM / R²

g = (4/9) × 9.8 ………[∵ from (1)]

g = 4.35 m/s²

Now,

Weight of body = mg

= 90 kg × 4.35 m/s²

= 392 N

Weight of 90 kg body on surface of Mars is 392 N

[Note: If weight of body on surface of earth is 90 N then on surface of Mars it’s weight is 90 × 4/9 = 40 N]