B) A timber beam is 120 mm wide and 200 mm deep and is used on a span of 4 m. The beam carriage uniformly distributed load of 3 kN/m run over the entire length. Find the maximum bending stress induced.

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Answer(b) 60 miles per hour;

The answer is 4f======since electrostatic force is given by    we let f be the electrostatic force when  r = 1 m    if we let  denote the electrostatic force when the distance is decreased so that r = 0.5m, then    we established earlier that f = kq₁q₂. therefore    the force will now be 4f.