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Please help me with 2 and 3. Thanks 2. An 82 -kg painter stands on a long horizo

ID: 1376894 • Letter: P

Question

Please help me with 2 and 3.

Thanks

2. An 82 -kg painter stands on a long horizontal board 1.55 m from one end. This 27-kg board is uniform, 5.5 m long, and supported at each end by vertical posts. (a) What is the magnitude of the total force provided by both posts? (b) With what force does the post that is closest to the painter push upward on the board? 3. An object attached to a ring is pulled across a horizontal frictionless surface. If the force constant (spring constant) of the spring is 45 N/m and the spring is stretched by 0.88 m when the object is accelerating at 1.4 m/s^2, what is the mass of the object? A) 28 kg B) 24 kg C) 31 kg D) 16 kg

Explanation / Answer

Let F1 be the support force nearest the painter and F2 be the other support force.

F1 + F2 = (82 + 27) g

F1(5.5) = 82 g (5.50 - 1.55) + 27(5.50 / 2)

F1 = g [82 (5.50 - 1.55) + 27 (5.50 / 2)] / 5.5

= 710.2 N

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kx = ma

m = kx / a = 45 * 0.88 / 1.4

= 28.3 kg