06 Midterm 2 Solutions Ch. 4-5, 10.5-6

06 Midterm 2 Solutions Ch. 4-5, 10.5-6 - 1. Concepts a. If...

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Version A 1. Concepts a. If an object is moving, must there be one or more forces acting on it? Briefly explain your answer, citing the appropriate physical law(s). No, it is not necessary for forces to act on an object for it to move. By the First Law, an object will remain in motion with a constant velocity if no forces act on it. b. .A car and a much larger truck collide in a traffic accident. The car is practically destroyed, and the truck is almost undamaged. Is this because the truck exerted a larger force on the car than the car did on the truck? Briefly explain your answer, citing the appropriate physical law(s). No, according to the Third Law, in any interaction (including a collision), the forces exerted by one object on another are equal and opposite.
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2. Statics a. A string is placed under tension by two identical, vertically hanging blocks of mass M = 7.50 kg, as shown. What is the tension in the string? Choose either mass. The forces acting on it are its weight, Mg downward, and the tension T in the string (upward). Since the objects are in equilibrium, the tension in the string must be Mg. T = Mg = (7.50 kg) (9.80 m/s 2 ) = 73.5 N b. A 10.0 kg painting is hung from the middle of a wire, as shown. After the painting is hung, the tension in the wire is 250. N. Find the angle α . Calculate the vertical forces at the point were the picture hangs on the wire. At that point: F y = T cos( α /2) + T cos( α /2) – Mg = 0. Mg = 2T cos(
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06 Midterm 2 Solutions Ch. 4-5, 10.5-6 - 1. Concepts a. If...

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