Tractive force for wheeled vehicle

[siludavid]

Homework Statement

a locomotive of mass 20 tonnes hauls a train of mass 200 tonnes up an incline of 1 in 200. the resistive force for the locomotive and the train is 40 Newtons per tonne. the train accelerates from rest to 60km/h in 2km.determine;
a) the tractive force of the locomotive
b) the drawbar pull between the locomotive and the train

Homework Equations

F=R+mgsinθ+ma from the Newton's second law of motion

The Attempt at a Solution

part a
mass=20000kg
sinθ=0.005
R=800
s=2000m
u=0
v=16.67m/s²
a=0.069m/s²
by substituting the equation above F will be 3161N or 3.161KN
now in the second part is where am getting difficulty in solving how can it be approached please

 

[tiny-tim]

welcome to pf!

hi siludavid! welcome to pf!

now in the second part is where am getting difficulty in solving how can it be approached please

(i haven't checked your figures)

the tractive force is found by using F_total = ma on the locomotive plus the train

the drawbar force is found by using F_total = ma on the train only

 

[siludavid]

where will the angle of inclination and the resistive force be used in that case

 

[tiny-tim]

where will the angle of inclination and the resistive force be used in that case

uhh?

same in both cases …

your F = ma equation (in both cases) is parallel to the slope

(if you're not sure, write out the equations to show us)

 

[siludavid]

according to me the tractive force minus the resistive force minus the resistive force due inclination which is mgsigθ because it always act on the opposite direction which will equal to ma that is;
F-R-mgsinθ=ma
therefore;
F=R+mgsinθ+ma
where R will be the resistive force together with mgsinθ

 

[tiny-tim]

F=R+mgsinθ+ma
where R will be the resistive force together with mgsinθ

yes

(same formula for both questions)

 

[siludavid]

now my problem is the drawbar remember it connects the train and the locomotive, will you find the tractive force in both locomotive and the train then find the difference between the two to get the pull or what should you do to get the drawbar pull

 

[tiny-tim]

now my problem is the drawbar remember it connects the train and the locomotive, will you find the tractive force in both locomotive and the train then find the difference between the two to get the pull or what should you do to get the drawbar pull

consider only the forces on the train …

you know what the acceleration is, and you know all the forces except the drawbar force