A train which normally runs at 120 km/h over a certain section of its journey is checked by a signal to 30 km/h over 2 km of the section. The train then covers 2 km and a further 3 km whilst recovering its normalspeed. Assuming the retardation and acceleration to be constant, find the time lost due to the check.

Question

A train which normally runs at 120 km/h over a certain section of its journey is checked by a signal to 30 km/h over 2 km of the section. The train then covers 2 km and a further 3 km whilst recovering its normalspeed.  Assuming the retardation and acceleration to be constant, find the time lost due to the check.

anonymous · Answer

draw a motion diagram.. it ll be easier to do the calculation