A driver having a definite reaction time is capable of stopping his car over a distance of 30 m on seeing a red traffic signal, when the speed of the car is 72 km/hr andover a distance of 10 m when the speed is 36 km/hr. Find the distance over which he can stop the car if it were running at a speed of 54 km/hr. Assume that his reaction time and the deceleration of the car remains same in all the three cases.

Options

A. 7000
B. 7
C. 5000
D. 5

Answer

B

Explanation

For a diatomic gas, `C_(v)=(5)/(2)R` and `C_(v)=(7)/(2)R`
The work done is an isobaric procers is
`W=p(V_(2)-V_(1))=nRT_(2)-nRT_(1)` or `T_(2)-T_(1)=(W)/(nR)`
The heat given in an isobaric process is `Q=nC_(p)`
`(T_(2)-T_(1))=nC_(p)(W)/(nR)=(7)/(2)`
`W=(7)/(2)xx2000J=7000J=7kJ`