Help with kinetic and dynamic principles

[shibby_ftw]

a train of mass 240 tonne is moving, at a speed of 84 km/h, up an incline of 1 in 90. the resistance to motion is 45 n per tonne. if power is removed, calculate the distance traveled along the incline before the train comes to rest

and

a railway wagon of mass 10 tonne traveling due east with a velocity of 14 kmh on a straight section of track collides with a second wagon of mass 12 tonne traveling due west at 3 km/h if thery are locked together after impact find the magnitude and direction of their common velocity.
i have no idea how to work it out, my notes have gone missing

i don't know where to begin, can someone help me with it please?
i don't mean do it for me i mean give me help in doing so, be it via email of instant message

 

[Lok]

a train of mass 240 tonne is moving, at a speed of 84 km/h, up an incline of 1 in 90. the resistance to motion is 45 n (N of coeff of friction?) per tonne. if power is removed, calculate the distance traveled along the incline before the train comes to rest

and

a railway wagon of mass 10 tonne traveling due east with a velocity of 14 kmh on a straight section of track collides with a second wagon of mass 12 tonne traveling due west at 3 km/h if thery are locked together after impact find the magnitude and direction of their common velocity.

1. Are your notes really missing :P.

2. If you have the mass and speed of an object you can compute it's energy. If you know that it loses energy through climbing and friction (or whatever that is) in a constant manner than time is easy.

3. This is a plastic collision problem and energy will be lost (out of the system) whatever remains will decide your speed. Momentum is more useful in this problem.

 

[shibby_ftw]

1. Are your notes really missing :P.

2. If you have the mass and speed of an object you can compute it's energy. If you know that it loses energy through climbing and friction (or whatever that is) in a constant manner than time is easy.

3. This is a plastic collision problem and energy will be lost (out of the system) whatever remains will decide your speed. Momentum is more useful in this problem.[/QUOTE]haha yeahh they are actually missing, i don't know the forumla required to work it out, or how towork it out at all. I am really bad at mechanical principles can you show me how to find out the forumla to use? are they based on the speed of the train and the friction?

and the resistance to motion is I am guessed its 240 tonne so there is 45N per tonne slowing it down so there's 10800N acting on the train? how are Newtons turned into speed? is it the same as gravity? so 9.81m/s ?and then times 10800? 105948 m/s divided by 1000 to make it km/h acting on the train so 105.948 km/h and its goes 84km/h so its slowing pretty fast? or am i well off?

 

[magwas]

if you ever loose the formula again, you will find it in Wikipedia:)
http://en.wikipedia.org/wiki/Kinetic_energy
http://en.wikipedia.org/wiki/Momentum

 

[shibby_ftw]

if you ever loose the formula again, you will find it in Wikipedia:)
http://en.wikipedia.org/wiki/Kinetic_energy
http://en.wikipedia.org/wiki/Momentum

thanks :) but i can't see anything about the 1 in 90 bit, can someone explain that?

 

[magwas]

I guess it wants to mean that on 90 units of horizontal offset, there is one unit of horizontal offset.
so tg(alpha)=1/90

 

[Lok]

haha yeahh they are actually missing, i don't know the forumla required to work it out, or how towork it out at all. I am really bad at mechanical principles can you show me how to find out the forumla to use? are they based on the speed of the train and the friction?

and the resistance to motion is I am guessed its 240 tonne so there is 45N per tonne slowing it down so there's 10800N acting on the train? how are Newtons turned into speed? is it the same as gravity? so 9.81m/s ?and then times 10800? 105948 m/s divided by 1000 to make it km/h acting on the train so 105.948 km/h and its goes 84km/h so its slowing pretty fast? or am i well off?

U cannot turn everything into everything else. N are a measure of force, not speed. There are relations to energy spentthat will help. First find out what energy the train has at 84 km/h. expressed in joules.