Question

Racing cars A and B began their last lap around a race track at speeds 115.2 km/hr and 172.8 km/hr respectively. If car A reaches the finishing line, 15 sec after carB, how long was the race track?

Answer 1

Step-by-step explanation:

Given : A's speed = 115.2km/hr

B's speed = 172.8km/hr

As time = 15 sec

Formula :speed = Distance traveled /time taken

Convert sec to hr = 15/60*60

1/240

A's time taken = 1/240 hr

As speed = distance traveled / time taken

115.2 km/ hr= D/ 1/ 240hr

= D *240 /1hr

115.2 km/hr/240 *1hr =D

0.48 km= D

As distance traveled by A and B is same

Bs distance =0.48km

Bs speed = distance traveled /time taken

172.8km/hr=0.48 km/time taken

time taken=0.48 km/172.8km/hr

=1/360 hr

Time taken in sec= 1*3600/360

=10 sec