Question

A freight train consists of two 8.00 x 105 kg engines and 45 cars with average masses of 5.50 x 105 kg. (a) Assuming the force of friction is 7.50 x 105 N, calculate the force each engine must exert to accelerate the train at 5.00 x 10-2 m/s2. (b) What is the magnitude of the force in the link coupling the 10th and 11th train cars?

Answer 1

Part a

We are going to determine the forces that act. Where the freight train only moves on the x axis. Applying Newton's second law, we obtain:

where

mass of the engines=

average mass of the cars =

friction force Fr =

acceleration (a) =

where the mass m is

m=mass of the engines + average mass of the cars x(45)

now we determine the force

where the force of each engine is:

force of each engine=F/2

force of each engine=

Part b

We will use the following free body diagram to determine the Tension ( magnitude of the force in the link)

m=mass of the 10 cars + mass of engines

mass of 1 car=

mass of the 10 cars=

now let's determine the tension T