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On a highway with a steep incline, the runaway truck ramp is constructed so that a vehicle that has a lost its breaks can stop. The ramp is designed to slow a truck in succeeding 20-m distances by 10km/hr, 12km/hr, 14 km/hr If the ramp is 160 m long, will it stop a truck moving at 120 km/h when it reaches the ramp.

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Intial Speed of truck = 120 km/hr

Order of successive Reduction of speed  : 10 , 12, 14, 16, 18, 20 , 22, 24  km/hr

Speed after each succesive reduction :  
        =  120-10,   120-(10+12),   120-(10+12+14),  .... km/hr
        =  110,   98,    84,  68,    50,   30,    8,  - 16  km/hr 
From the above we can conclude that after 7th reduction in speed, speed of truck becomes 8 km/hr

In 8th step, there is maximum possible reduction in speed is 24 km/hr. So, after 8km/hr reduction in 8th step truck will stop. 
So, in the 160 m  truck will definately stop .

GOLDEN POINT :(-16 km/hr) symbolise that if intial spped of truck is 136km/hr than also truck will stop but  if speed exceds 136km than truck will not stop within 160 m

Posted by

Deependra Verma

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