A block of mass 40 kg resting on a horizontal surface just begins to slide when a horizontal force of 120 N is applied to it.
A block of mass 40 kg resting on a horizontal surface just begins to slide when a horizontal force of 120 N is applied to it. Once the motion starts, It can be maintained by a force of 80 N. Determine the coefficients of static friction and kinetic friction
(g = 9.8 m/s2)
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Given: FL = 120N, Fk = 80N, m = 40 kg, g = 9.8 m/s2
To find:
i. Coefficient of static friction (μS)
ii. Coefficient of kinetic friction (μk)
Formulae:
i. μs = \(\frac{F_L}{N}\)
ii. μk = \(\frac{F_K}{N}\)
Calculation:
From formula (i) we get.
N = mg = 40 × 9.8 = 392 N
∴ μs = \(\frac{F_L}{N}=\frac{120}{392}\) = 0.306
From formula (ii) we get,
∴ μk = \(\frac{F_k}{N}=\frac{80}{392}\) = 0.204
1. The coefficient of static friction is 0.306.
2. The coefficient of kinetic friction is 0.204.
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