JEE MainPhysicsGravitationMCQ+4 / −1
A box weight 196 N on a spring balance at the north pole. Its weight recorded on the same balance if it is shifted to the equator is close to (Take g = 10 ms–2 at the north pole and the radius of the earth = 6400 km) :
- A194.32 N
- B195.66 N
- C195.32 N
- D194.66 N
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Correct answer: C
- Weight at the north pole
At the north pole, there is no reduction in apparent weight due to Earth's rotation.
Given:
So the mass of the box is
- Effect at the equator
At the equator, the spring balance reads the apparent weight:
Since the problem gives at the north pole, we take gravitational acceleration approximately same, and subtract centrifugal acceleration at the equator.
- Compute centrifugal acceleration
Angular speed of Earth: with
Thus,
Radius of Earth:
Now,
Using the standard value,
- Apparent acceleration due to gravity at equator
- Apparent weight at equator
This is closest to
- Option check
- A: — too low
- B: — too high
- C: — correct
- D: — too low
Therefore, the correct option is C.
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