Homework 3_Graded - PROBLEM 12.18 The system shown is...

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PROBLEM 12.18 The system shown is initially at rest. Neglecting the masses of the pulleys and the effect of friction in the pulleys, determine (a) the acceleration of each block, (b) the tension each cable. 10 kg SOLUTION Let Y be positive downward position for all blocks. Constraint of cable attached to mass A: YA + 3YB == constant or Constraint of cable attached to mass C: Ye + Y B == constant T.... t A e. Y Y For each block + ~ "'£F == ma: mBg - 3(mAg 3mAaB) (meg - meaB) mBaB mB 3mA -me ==30-30-10(9.81) g + 9mA + me 30 + 90 + 10 (a) Accelerations. a B == 0.755 m/s 2 t <III aA == -(3)(-0.75462) == 2.26 m/s 2 a A 2.26 m/s 2 ~ ae == -(-0.75462) == 0.755 m/s 2 8 e == 0.755 m/s 2 ~ (b) Tensions. TA = (10)(9.81) (10)(2.26) == 75.5 N Te == (10)(9.81) - (10)(0.755) = 90.6N
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PROBLEM 12.37 During a hammer thrower's practice swings, the 16~lb head A of the hammer revolves at a constant speed v in a horizontal circle as shown. If p 3 ft and () = 60°, determine (a) the tension in wire Be, (b) the speed ofthe hammer's head. SOLUTION (a) "fFy 0: Tsin() - W = 0 T = W 16 or T = 18.481b <l1li sin() sin 60° T 2 v Tcos() = m- p pTcos() pW cos() m msin()
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Homework 3_Graded - PROBLEM 12.18 The system shown is...

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