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A body of mass 1 kg rests on a horizontal floor with which it has a coefficient of static friction 1/√3. It is desired to make the body move by applying the minimum possible force F N. The value of F will be ________. (Round off to the Nearest Integer) [Take g = 10 m s⁻²]

1. 5
2. 6
3. 7
4. 8

Correct answer: 5

Solution

The least force to start motion is applied at angle theta = arctan(mu): F_min = mu m g / sqrt(1+mu^2). With mu = 1/sqrt(3), m = 1, g = 10: F_min = (10/sqrt(3))/sqrt(4/3) = 5 N.

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