# A car gave a reading of distance 2000 km at the start of at trip and 2288km at the end of the trip.if the trip took 8 hrs ,calculate the average speed of the car in m/s2]on the 100 m track ,a train travels the first 30 km at the uniform speed of 30km/h.how fast must the train travel the next 70 km so as to average 40 km/h for the entire trip?

1
by charitamantri
these are two different problems !!

• Brainly User
2014-05-19T13:33:16+05:30
Average speed=total distance travelled / total time
here total distance will be 288km
time taken=8hours
=>288/8
=36  km/h
=10m/s

2)
first 30 km => v = s / t
30 = 30 / t =>t = 1 hr
next 70 km
let velocity be x
v = s / t =>x = 70 /t
t = 70 / x
total time taken i=> 1 + 70/ x = (70 + x) / x
dist. travelled is 100km
avg. velovity = total dist / total time
40 = 100|(70 + x) / x => 40. (70+x) / x = 100
2800 + 40x - 100x = 0   => - 60x = - 2800 => x = - 2800 / -60
x = 45.55 km/hr
in the first problem to find the total distance
288 km?? y did u subtract
coz its starting at 2000 and ending at 2288km
ohh k ..thnk u
i have 1 doubt....if the avg speed is 40Km/hr...and the total distance to cover 100Km....so the time taken should be 2.5hrs.....den if the train travels for 1Hr at a speed of 30.....remaining distance is 70Km.....den the train should travel 70Km in 1.5Hrs right.....70/1.5 = 46.667.....