on a 60 km straight road a bus travels the first 30km with a uniform speed of 30km/h.How fast must the bus travel the next 30km so as to have average speed of 40km/h for the entire trip ?
Answers
Answer:
20km
Explanation:
speed = distance/time
speed=?,distance=60km,time is not given so,
time=1 hour
but according given question speed =30km for half journey
30km=60/1==
30x=60*1=60
x=60/30=20km
x=20
Given that, on a 60 km straight road a bus travels the first 30 km with a uniform speed of 30 km/h.
(Total distance covered by bus = 60 km, d1 = 30 km, d2 = 30 km and average speed = 40 km/hr)
We have to find the speed of the bus.
Time = Distance/Speed
Case 1)
t1 = 30/s1
Case 2)
t2 = 30/s2
Average speed is defined as the ratio of total distance covered with respect to total time taken.
Total distance covered by the bus = 60 km (30+30)
Total time taken by bus = t1 + t2
Average speed = (Total distance covered)/(Total time taken)
Substitute the known in the above formula,
40 = 60/(30/s1 + 30/s2)
"On a 60 km straight road a bus travels the first 30km with a uniform speed of 30km/h"
Means, s1 = 30 km/hr
→ 40 = 60/(30/30 + 30/s2)
→ 40 = 60/(1 + 30/s2)
→ 2 = 3/(1 + 30/s2)
→ 2/3 = 1/(1 + 30/s2)
→ 3/2 = 1 + 30/s2
→ 1.5 - 1 = 30/s2
→ 0.5 = 30/s2
→ s2 = 30/0.5
→ s2 = 60
Therefore, the speed of the bus during the entire trip is 60 km/hr.