Home › Tamil Nadu SSLC (Class 10) › Physics › Laws of Motion › At what height from the centre of the Earth (rad…
At what height from the centre of the Earth (radius R) does the acceleration due to gravity become one-fourth of its surface value?
A4R
BR/2
C2R
DR/4
Answer & Solution
Correct answer: C. 2R
1. Since g is proportional to 1/r², g'/g = R²/r'², where r' is the distance from the centre.
2. Set g' = g/4: then 1/4 = R²/r'², so r'² = 4R².
3. Taking the root, r' = 2R from the centre of the Earth.
4. Rule out 4R: that would make g'/g = 1/16, not 1/4.
5. Rule out R/2: a smaller radius gives a larger g, not a quarter.
_Source: Samacheer Kalvi (TN SCERT) Class 10 Science, Unit 1 "Laws of Motion", p.19_
Related questions
A constant force of 6 N acts for 4 s on a 2 kg body initially at rest. The kinetic energy A stone of mass 0.5 kg is whirled in a horizontal circle of radius 1 m at constant angularA car of mass 1000 kg accelerates from rest to 20 m s⁻¹ in 5 s on a level road. The net hoA man weighing 50 kg jumps off a stationary boat of mass 250 kg into water with a horizontNewton's third law states that 'action and reaction are equal and opposite'. The most accuTwo identical billiard balls strike a smooth rigid wall with equal speeds u. Ball A strikeA force F acts on a particle making an angle θ with its instantaneous velocity. The componA cricketer draws his hands back while catching a fast ball. The physical reason is that: