Exams › JEE Main › Physics

Two identical masses, each m, are suspended from the two pans of a balance. The two pans hang at slightly different heights, the vertical separation between them being h. Expressing the answer through the mean density rho of the earth, the error in weighing (the apparent difference in the two weights) is:

1. (8/3)*pi*G*rho*m*h
2. (4/3)*pi*G*rho*m*h
3. (1/3)*pi*G*rho*m*h
4. pi*G*rho*m*h

Correct answer: (8/3)*pi*G*rho*m*h

Solution

The two masses sit at heights differing by h, so they experience slightly different g. The weighing error is m times the change in g over h, with dg/dr = -2g/R at the surface. Writing g in terms of rho eliminates R.

Related JEE Main Physics questions

• A satellite of mass m moves in a circular orbit around the Earth at an altitude x above the Earth's surface. If g denotes the acceleration due to gravity at the Earth's surface, then the satellite's orbital speed is
• A particle is launched vertically upward from Earth’s surface with speed equal to three-fourths of the escape speed. The maximum distance of the particle from the Earth’s center is (take Earth’s radius as R):
• If Earth’s radius became 1% smaller while its mass stayed unchanged, what would happen to the acceleration due to gravity at the surface?
• The Moon takes about 29 days to complete one revolution around the Earth. If the Moon’s mass were doubled while every other factor stayed the same, its orbital period would be approximately
• Let the Earth have mean radius R, angular velocity ω about its own axis, and surface gravitational acceleration g. The orbital radius of a geostationary satellite is:
• Assume the Earth is a uniform sphere. Scientist A descends into a mine, while scientist B rises in a balloon. As they move, the gravitational field experienced by A keeps decreasing and the field experienced by B also keeps decreasing. Which statement best describes their rates of decrease?

⚔️ Practice JEE Main Physics free + battle 1v1 →