Question

What would be the magnitude of the acceleration due to gravity on the surface of the earth if the radius of the earth were reduced by 20%?

(a) 9.81 m/s^2

(b) 12.26 m/s^2

(c) 15.33 m/s^2

(d) 49.05 m/s^2

The question was posed to me by my school principal while I was bunking the class.

My question comes from Acceleration due to Gravity of the Earth topic in division Gravitation of Physics – Class 11

Answer 1

Correct answer is (c) 15.33 m/s^2

Easy explanation: g = (G*M1)/R^2;

M1 = Mass of the earth

R = Radius of the earth

We know; g = 9.81 m/s^2

If the radius is reduced by 20% then the new radius is 80% of the original one;

New radius = 0.8R

Therefore, new acceleration;

g / (0.8 x 0.8) = 9.81 / 0.64

= 15.33 m/s^2.