Question 5.31:
A train runs along an unbanked circular track of radius 30 m at a speed of 54 km/h. The mass of the train is 106
kg. What provides the centripetal force required for this purpose – The
engine or the rails? What is the angle of banking required to prevent
wearing out of the rail?
Solution:
Radius of the circular track, r = 30 m
Speed
of the train, v
= 54 km/h = 15 m/sRadius of the circular track, r = 30 m
Mass of the train, m = 106 kg
The centripetal force is provided by the lateral thrust of the rail on the wheel. As per Newton’s third law of motion, the wheel exerts an equal and opposite force on the rail. This reaction force is responsible for the wear and rear of the rail
The angle of banking θ, is related to the radius (r) and speed (v) by the relation:
tan θ = v2 / rg
= 152 / (30 X 10)
= 225 / 300
θ = tan-1 (0.75) = 36.870
Therefore, the angle of banking is about 36.87°
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