PROBLEM 13-27 (page 126, 12th edition) The mass of block A is 100 kg. The mass of block B is 60 kg. The coefficient of static friction between block B and the inclined plane is 0.6. The coefficient of kinetic friction between block B and the inclined plane is 0.4. A and B are released from rest. • Determine the acceleration of block A and the tension in the cord. Neglect the mass of the pulleys and the cord. E O C D B A 60° PROB13_027.jpg Copyright @ 2010 Pearson Prentice Hall, Inc.
PROBLEM 13-27 (page 126, 12th edition) DIAGRAMS B 60 kg A 100 kg 0
13-27 (page 126, 12th edition) COMPLETION OF PROBLEM · Assume block A accelerates up. Equation of motion for block A : ?F = ma : y y 3T -m g = m a · Equation of motion for block B: ! F = ma : X mpgsin " #T # UN = map X y N "mpgcos # = 0 y ! F = ma : · Dependent motion: ap = 3a 1A · Eliminate T and solve for a : $3mp( sin!" ucos!) "mA &og a = 'A mA+9mB Then T = mAg+a 3 · Numerical results: : a > 0: A accelerates up as assumed. s : a =305mm/s2 T = 337N