Question(II) A train locomotive is pulling two cars of the same mass behind it, Fig. 4-43. Determine the ratio of the tension in the coupling (think of it as a cord) between the locomotive and the first car to that between the first car and the second car , for any nonzero acceleration of the train.
FIGURE 4-43 Problem 37.
Studdy Solution
STEP 1
1. The train locomotive is pulling two cars of the same mass.
2. The tension in the coupling between the locomotive and the first car is .
3. The tension in the coupling between the first car and the second car is .
4. The train is accelerating with a nonzero acceleration .
5. The mass of each car is .
STEP 2
1. Analyze the forces acting on the second car.
2. Analyze the forces acting on the first car.
3. Determine the expressions for and .
4. Calculate the ratio .
STEP 3
Analyze the forces acting on the second car. The only horizontal force acting on the second car is the tension . According to Newton's second law, the net force is equal to the mass times the acceleration:
STEP 4
Analyze the forces acting on the first car. The first car is being pulled by the tension and is pulling the second car with tension . The net force on the first car is:
STEP 5
Determine the expressions for and . From Step 1, we have:
From Step 2, solve for :
Substitute into the equation:
STEP 6
Calculate the ratio :
The ratio of the tension in the coupling between the locomotive and the first car to that between the first car and the second car is:
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