A train engine pulls out of a station along a straight horizontal track with five identical freight cars behind it, each of which weighs 88.0 kN. The train reaches a speed of 13.0 m/s within 6.50 min of starting out. Assuming the engine pulls with a constant force during this interval, and ignore air resistance and friction on the freight cars. Find the tension in the coupling between cars 2 and 3.

Give answer in kN please!!!

Three cars are being pulled (cars, 3,4,5)

tension= massthreecars*acceleration

so figure acceleration.

acceleartion= changevelocyt/time

change minutes to seconds in that.

isnt the velocity already 13.0 m/s for all of them and a=9.8 ??? bobpursley are you sure cuz your confusing me!!!

To find the tension in the coupling between cars 2 and 3, we can consider the forces acting on each car.

First, let's calculate the total mass of the train. Since each freight car has the same weight, the total weight of all five cars is:

Weight of one car = mass * acceleration due to gravity
Weight of one car = (88.0 kN) / (9.8 m/s²) ≈ 8.98 metric tons

Total weight of all five cars = 5 * 8.98 metric tons = 44.9 metric tons

Next, let's calculate the net force acting on the train. Net force is equal to the mass of the train multiplied by its acceleration:

Mass of the train = total weight / acceleration due to gravity
Mass of the train = (44.9 metric tons) / (9.8 m/s²) ≈ 4.58 metric tons

Net force = mass * acceleration
Acceleration = change in velocity / time
Acceleration = (13.0 m/s - 0) / (6.50 min * 60 s/min)
Acceleration ≈ 0.036 m/s²

Net force = (4.58 metric tons) * (0.036 m/s²) ≈ 0.165 metric tons

Now, the tension in the coupling between cars 2 and 3 is equal to the force required to accelerate the third car. Since the force is constant, we can assume that the net force acting on car 3 is the same as the net force acting on the entire train.

Tension in the coupling between cars 2 and 3 = net force
Tension in the coupling between cars 2 and 3 ≈ 0.165 metric tons

To convert metric tons to kilonewtons, we can use the conversion factor:

1 metric ton ≈ 9.8 kN

Tension in the coupling between cars 2 and 3 ≈ (0.165 metric tons) * (9.8 kN / metric ton)
Tension in the coupling between cars 2 and 3 ≈ 1.617 kN

Therefore, the tension in the coupling between cars 2 and 3 is approximately 1.617 kN.