Understanding Forces in a Train System

[AakashPandita]

but the net force is created by the engine...everywhere...so the acceleration due to net force should be the same everywhere...isn't it?

 

[Doc Al]

but the net force is created by the engine...everywhere...so the acceleration due to net force should be the same everywhere...isn't it?

Yes, the acceleration is the same everywhere.

 

[tiny-tim]

Aakash, F = ma and E - F = Ma …

does that mean anything to you? ​

 

[AakashPandita]

and the net force too?

 

[Doc Al]

and the net force too?

The 'thing' you set equal to 'ma' is always the net force.

For the four wagons, the net force is simply F (since that's the only force acting).

For the engine and wagon 1, the net force is E - F.

 

[AakashPandita]

what is E over here?

 

[tiny-tim]

what is E over here?

Aakash, what do you think it is?

Look at what Doc Al and I have already said.

What is it likely to be?

What sort of thing is it?

You have to do some work. ​

 

[AakashPandita]

Is E= mass of wagon2+3+4+5 x acceleration?

 

[tiny-tim]

Is E= mass of wagon2+3+4+5 x acceleration?

Aakash, never mind (for the moment) what E is equal to.

The question was, what is E ?

(ie what are we talking about)

 

[AakashPandita]

the net force on the engine+wagon1

 

[tiny-tim]

the net force on the engine+wagon1

Aakashm, are you reading what we have been saying? …

For the engine and wagon 1, the net force is E - F.

Again, what do you think E is?

 

[AakashPandita]

the force exerted by the engine?

 

[Doc Al]

the force exerted by the engine?

Once again, the forces on 'engine + wagon 1' are:

E = the force of the tracks on the engine (which acts in the forward direction)
F = the force from wagon 2 (which acts towards the rear)