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A car and a truck are going on a straight road each having a velocity of 72 km/h. The car cannot come to a stop in less than 3.0 sec and the truck takes 5.0 seconds time to stop on the high-way. The car is behind the truck. The truck gives a signal for stopping at a tollplaza. What should be the least distance of the car from the truck so that it does not bump onto the truck? (Take human response time to be 0.5 sec) |
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Answer» 1.25 m Then`a_t=(20)/(5)=4 ms^(-2)` and `a_c=(20)/(3) ms ^(-2)` Applyings v=u+at For truck `v_t=20-4t` `=-(1)/(2)XX(20)/(3)[(5)/(4)-0.5]^(2)` `S_(C)`=23.125 m Thus `S_(c)-S_(t)`=1.25 m. Hence the speed of the car will always be less than the truck and they will never collide if they maintain these speeds |
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