Question

In the Daytona 500 auto race, a Ford Thunderbird and a Mercedes Benz are moving side by side down a straightaway at 72.0 m/s. The driver of the Thunderbird realizes that she must make a pit stop, and she smoothly slows to a stop over a distance of 250 m. She spends 5.00 s in the pit and then accelerates out, reaching her previous speed of 72.0 m/s after a distance of 360 m. At this point how far has the Thunderbird fallen behind the Mercedes Benz, which has continued at a constant speed?

Answer 1

deceleration while stoping, a = (0^2 - 72^2)/(2*250)

   = -10.368m/s^2

time taken to stop, t1 = ( 0 - 72)/(-10.368)

= 6.94 s

time taken at rest, t2 = 5s,

acceleration while moving again, a = (72^2 - 0^2)/(2*360)

   = 7.2 m/s^2

time taken to stop, t1 = ( 72-0)/(7.2)

= 10 s

total time taken, t = t1 + t2 + t3

= 6.94 + 5 + 10

= 21.94 s

distance travelled by benz car = 72*21.94

= 1580 m

distance between thunder bird and benz car = 1580 - (250+360)

= 970 <<<<<<<<<<<<-----------Answer