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**1. Homework Statement**

A tugboat pulls two barges down the river. The barge connected to the tugboat, carrying coal, has an inertia of 2.0 × 105 kg, and the other barge, carrying pig iron, has an inertia of 3.1 × 105 kg.The resistive force between the coal barge and the water is 8.0 × 103 N, and the resistive force between the pig iron barge and the water is 1.0 × 104 N . The common acceleration of all three boats is 0.40 m/s2. Even though the ropes are huge, the gravitational force exerted on them is much smaller than the pulling forces.What is the tension in the rope that connects the tugboat to the coal barge?

**2. Homework Equations**

F=ma

**3. The Attempt at a Solution**

F=( 2.0x10^5)(0.4)- 8.0x10^3

= 7200N