A block rests on a rough inclined plane making an angle of 30^ with the horizontal. The coefficient of static friction between the block and the plane - Physics MCQ AIEEE 2004 2026 | ExamTest.live

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A block rests on a rough inclined plane making an angle of 3 0^{\circ} with the horizontal. The coefficient of static friction between the block and the plane is 0.8 . If the frictional force on the block is 10 N, the mass of the block (in kg) is: (take g = 10 m/s^{2})

Solution & Step-by-step Explanation

Since the block is resting (in equilibrium), the frictional force balances the component of weight along the incline. f = m g sin θ Given f = 10 N, θ = 3 0^{\circ}, and g = 10 m/s^{2} : 10 = m \times 10 \times sin 3 0^{\circ} 10 = 10 m \times 0.5 10 = 5 m ⟹ m = 2 kg Checking validity: Max static friction f_{s} = μ m g cos θ = 0.8 \times 2 \times 10 \times 0.866 \approx 13.8 N . Since 10 < 13.8, the block indeed remains at rest.

Try it yourself before checking the explanation above.

A block rests on a rough inclined plane making an angle of 3 0^{\circ} with the horizontal. The coefficient of static friction between the block and the plane is 0.8 . If the frictional force on the block is 10 N, the mass of the block (in kg) is: (take g = 10 m/s^{2})

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4.0

1.6

2.5

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