A block of mass 70 k g is kept on a rough horizontal surface and coefficient of static friction between block and surface is 0.4 . A man is trying to pull the block by applying a horizontal force. If the surface exerts a force F on the block then

Question

A block of mass 70 k g is kept on a rough horizontal surface and coefficient of static friction between block and surface is 0.4 . A man is trying to pull the block by applying a horizontal force. If the surface exerts a force F on the block then, F must be 700 N, F must be 280 N, 700 N ≤ F ≤ 754 N, F maybe greater than 754 N

MARKS App · Accepted Answer

Normal reaction, N = m g = 700 N Limiting friction, f L = μ m g = 0.4 700 f L = 280 N F = N 2 + f 2 When f = 0 , F m i n = N When f = f L , F m i n = 700 N F m a x = 700 2 + 280 2 F m a x = 754 N ∴ 700 N ⁡ ≤ F ⁡ ≤ 754 N

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