The figure below shows a train with 3 compartments only. Each of the

Question

compartments has a mass of 30 tons . Two of them are motor cars while the
other one is a trailer car. Each of the motor cars provides a driving force F. Suppose the train is
accelerating at 1.5 m s−2 and the friction on each car is 2 ¡Ñ 10^4 N.
F-> F->
|trailer car|----|motor car|----|motor car|
OO OO OO OO OO OO

(a) Find the driving force F.
(b) What is the tension between
(i) the motor car and the trailer car; and
(ii) two motor cars?

My answers are

(a) F - friction of 3cars = ma
F = 195000N <-- should it be divided by 2? because there are 2 motor car providing a force. Actually I don't clearly understand what the question is asking.(driving force of the train or one motor compartments?)

(b)(i) T(trailer to motor) - friction of trailer = ma
T(trailer to motor) = 65000N

(ii) 65000N * 2 = 130000N <--is that ok? because mass of all cars are the same.

are they correct? thanks !!!!

Answer 1

sorry that the graph I tried to make totally sucks. I meant the cars in the middle and right are motor cars and the train is accelerating to the right hand side.