A `8000kg` engine pulls a train of `5 wagons`, each of `2000kg`, along a horizontal track. If the engine exerts a force of `40000N` and the track offers a frictional force of `5000N`, then calculate:
(a) the net accelerating force, (b) the acceleration of the train, and
(c ) the force of wagon 1 on wagon 2.

Options

A. `50000 N, 2.0 m/s2, 15000 N
B. 35000 N, 1.94 m/s^2, 15520 N
C. 50000 N, 2.5 m/s^2, 9000 N
D. NONE

Answer

B

Explanation

Here, mass of engine, `m_(1)=8000 kg `
mass of 5 wagon, `m_(2)= 5xx2000 kg = 10000 kg`
force exerted by the engine, `F = 40000N` , frictional force, `f=5000N`
(a) Net accelerating force `= F-f = 40000-5000 = 35000`
(b) The acceleration of the train `a = ("net force")/("total mass of engine and wagon")= (F-f)/(m_(1)+m_(2)) = (35000)/(18000)= 1.94 m//s^(2)`
(c) Force of wagon 1 on wagon 2 = mass of 4 wagon (behind wagon 1) `xx` acceleration
`4xx2000xx1.94= 15520N`