99 Percentile Qs Bank for JEE MainPhysicsGravitation
On a planet, whose size is the same and mass is three times as that of the earth, find the amount of work done to lift 5   kg mass vertically upwards through 10   m on the planet. The value of g on the surface of earth is 9 . 8   m   s - 2 ​ .
Options
- A1 , 470   J
- B1 , 520   J
- C170   J
- D1 , 420   J
Correct answer
A. 1 , 470   J
Step-by-step solution
Let, M and R be the mass and radius of the earth, respectively. Then, g = G M R 2 . . . i ⁡ Now, mass of the planet, M ' = 3   m and radius of the planet, R ' = R . Let, g ' be the acceleration due to gravity on the surface of planet. Then, g ' = G M ' R ' 2 . . . ii Dividing the equations ( ii ) by ( i ) , we have g ' g = M ' M × R 2 R ' 2 = 3 M M × R 2 R 2 = 3 or g ' = 3 g = 3 × 9 . 8 = 29 . 4 m   s - 2 Now, the amount of work done to lift a m