In Problems 70 through 72 you are given the dynamics equations that are used to solve a problem. For each of these, you are to
a. Write a realistic problem for which these are the correct equations.
b. Draw the free-body diagram and the pictorial representation for your problem.
c. Finish the solution of the problem.
70. -0.80n = (1500 kg)ax
n - (1500 kg)(9.80 m/s2) = 0
71. T - 0.20n - (20 kg)(9.80 m/s2) sin 20°
= (20 kg)(2.0 m/s2)
n - (20 kg) (9.80 m/s2) cos 20° = 0
72. (100 N) cos 30° - fk= (20 kg)ax
n + (100 N) sin30° - (20 kg)(9.80 m/s2) = 0
fk= 0.20n
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