A train have a Mass of M.It pulls in a horizontal plane against the resistance force R.The Engine works at the same rate of H, (U<$\displaystyle \frac{H}{R}$)
1.When R is constant,Show the time take by the train to assume U from rest is $\displaystyle \frac{MH}{R^2}ln\frac{H}{H-RU}-\frac{MH}{R}$

In this problem, Let P be the pull of Engine Then , (P)(U)=H Is It Correct Or Not???????