Banking Q (2 Viewers)

[azureus88]

A railway line around a circular arc of radius 800m is banked by raising the outer rail h metres above the inner rail, where the distance between the rails is 1.5 metres. When the train travels around the curve at 10m/s, the lateral thrust on the inner rail is equal to the lateral thrust on the outer rail when the speed is 20m/s. Calculate the value of h and the speed of the train when no lateral thrust is exerted on the rails.

Can someone explain why the inner rail exerts a lateral thrust up the slope and the outer rail exerts a lateral force down the slope?

Thanks

NB: no need for a full solution

 

[lolokay]

when the train travels at 10m/s, the velocity is too small to keep it moving in a circle, so it has to be kept up by the inner rail (ie. the inner rail exerts a force up the slope)

when the train travels at 20m/s, the velocity is too large to keep it moving in a circle, so it has to be kept down by the outer rail (ie. the outer rail exerts a force down the slope)

 

[azureus88]

when the train travels at 10m/s, the velocity is too small to keep it moving in a circle, so it has to be kept up by the inner rail (ie. the inner rail exerts a force up the slope)

when the train travels at 20m/s, the velocity is too large to keep it moving in a circle, so it has to be kept down by the outer rail (ie. the outer rail exerts a force down the slope)

How do you know that from the question?

 

[lolokay]

if the velocity is too small, then it would start to move down the slope, so it needs to be kept up by the inner rail (which is pretty much what i said before so i don't know if it answers your question). the fact that it needs to have the rail apply an upwards force implies that it is moving too slowly