a car covers half a distnace in a speed of 40 km/hr nd other half of the distance at a speed of 60km/hr.find the average spped of the car.
Asked by anneshwa | 25th May, 2012, 09:40: PM
The car covers the firsthalf at the v1 speed, of 40 km/h, and the other half at the v2 speed, of 60 km/h.
The first half of distance is covered in the time t1, and the other halfin the time t2.
We'll write the formula of speed:
v = x/t (1)
v1 = (x/2)/t1
We'll substitute v1:
40 = (x/2)/t1
t1 = x/80 hour
v2 = (x/2)/t2
We'll substitute v2:
60 = (x/2)/t2
t2 = x/120 hour
Now, we'll write the average speed:
av. v = total distance covered/total time taken
av. v = x/(t1+t2)
We'll substitute t1 and t2:
av. v = x/(x/80+x/120)
av. v = 80*120/(80+120)
av. v = 9600/200
av. v = 48 Km/h
The average speed of the car is av. v = 48 Km/h.
The car covers the firsthalf at the v1 speed, of 40 km/h, and the other half at the v2 speed, of 60 km/h.
The first half of distance is covered in the time t1, and the other halfin the time t2.
We'll write the formula of speed:
v = x/t (1)
v1 = (x/2)/t1
We'll substitute v1:
40 = (x/2)/t1
t1 = x/80 hour
v2 = (x/2)/t2
We'll substitute v2:
60 = (x/2)/t2
t2 = x/120 hour
Now, we'll write the average speed:
av. v = total distance covered/total time taken
av. v = x/(t1+t2)
We'll substitute t1 and t2:
av. v = x/(x/80+x/120)
av. v = 80*120/(80+120)
av. v = 9600/200
av. v = 48 Km/h
The average speed of the car is av. v = 48 Km/h.
Answered by | 25th May, 2012, 10:02: PM
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