How Long Will It Take for a Car to Catch Up to a Truck If Both Are Moving?

[wadesweatt]

A car traveling 115 km/h is 150 m behind a truck traveling 75 km/h. How long will it take the car to reach the truck?

Ok I think I am doing this right but I can't get it to tell me I'm correct on the online homework. See what you think about what I'm doing:

150m= .15km

so then, 115x=75x+.15

which yields x= .15 / 40 = .00375 s

Is this not right? It says I am incorrect. Is there some procedure I am leaving out?

 

[alphysicist]

Hi wadesweatt,

A car traveling 115 km/h is 150 m behind a truck traveling 75 km/h. How long will it take the car to reach the truck?

Ok I think I am doing this right but I can't get it to tell me I'm correct on the online homework. See what you think about what I'm doing:

150m= .15km

so then, 115x=75x+.15

which yields x= .15 / 40 = .00375 s

The unit for this answer is incorrect. Look at what units the velocities have, and then you'll need to convert this answer to seconds (if that's what is asked for).