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A car A is travelling on a straight leve...

A car A is travelling on a straight level road with a uniform speed of 60 km/h. It is followed by another car B which in moving with a speed of 70 km/h. When the distance between then is 2.5km, the car B is given a deceleration of `20(km)/(h^2)`. After how much time will B catch up with A

A

1 hr

B

`(1)/(2)`hr

C

`(1)/(4)` hr

D

`(1)/(8)` hr

Text Solution

Verified by Experts

The correct Answer is:
B
Let car B catches, car A after `t` sec, then
`60t+2.5=70t-(1)/(2)xx20xxt^2`
`implies10t^2-10t+2.5=0impliest^2-t+0.25=0`
`t=(1+-sqrt(1-4xx(0.25)))/(2)=(1)/(2)hr`
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