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As shown in the figure, the mass of flat car B is m = 4kg, and the mass of object a on the car is m = 1kg. The dynamic friction coefficient between them is μ = 0.4, and the maximum static friction is F0 = 5N? (2) When f = 26n, what is the friction between a and B? What are the accelerations of a and B at this time?
Let am = f0m = 51m / S2 = 5m / S2, the maximum value of pulling force F is FM = (M + m) am = (4 + 1) × 5N = 25N. (1) since f = 15N < FM, AB will move together, and the friction between AB is static friction. For the whole analysis, f = (M + m) a is isolated. For the object a, f = ma is solved, and F = 3N. (2) because f = 26n > FM, AB will move relatively, and the friction between AB is static friction F = μ mg = 0.4 × 1 × 10N = 4N. For a, AA = FM = 41m / S2 = 4m / S2. For B, ab = f − FM = 26 − 44m / S2 = 5.5m/s2. A: (1) when f = 15N, the friction between a and B is 3N. (2) when f = 26n, the friction between a and B is 4N, and the acceleration of a and B is 4m / S2 and 5.5m/s2 respectively
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