THE SPEED....

The distance travel from A to B is 30x, where x is the time. The time taken from B to A is 30x/20= 1.5x.The average speed is 60x/2,5x = 24km/h.

If the distance is 'x'

Average Speed will be, Av. Speed (Km/H) = [x/30 + x/20] / 2 = [50x/600] / 2 = x/24
Av Speed = 24 Km/H (where, x = 1, 2, 3, ....)

Avg speed=2xy/(x+y)

Say, a car travels at S1 mph on a trip and at S2 mph on return trip. What is its average speed for the entire trip?

Solution:

* Don't fall in the trap of just averaging the 2 speeds. Overall average speed is not (S1+S2)/2.

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Total average speed is simply = Total distance/Total time

Lets say,

D = distance travelled by the car in EACH direction

t1 = time spent on onward trip

t2 = time spent on return trip

Thus, the total distance travelled by the car = D+D= 2D

And, by the formula, Speed = Distance/Time

S1 = D/t1 => t1 = D/S1

S2 = D/t2 => t2 = D/S2

Total average speed = Total Distance/Total time = 2D/(t1+t2) = 2D/(D/S1+D/S2) =

2S1*S2/(S1+S2)

so put values we get 20*30/50=24

Here the distance between point A & B are not given,so taking travelling points suppose 30 KM, going from A to B will take 2 hr,while coming back from B to A will take 1 hr 30 mts. So travelling 60 Km takes 150 mts. Avg speed is thus 60/150 =24 Km/hr Ans

K.K.GARG,india

The distance travel from A to B is 30x, where x is the time. The time taken from B to A is 30x/20= 1.5x. The average speed is 60x/2,5x = 24km/h.

1/avg velocity = 1/N (1/V1 +1/V2)

Where N= one time journey (1/2), V1 = first velocity (30), V2=second velocity (20)

If the distance from A to B is 60 km, then it took him 2 hours to get to point B and 3 hours to get back. So if he traveled 120 km in 5 hours, his average speed is 24 km/h.

S: distance from A to B (2S)

T: time from A to B + time from B to A

v1 = 30km/h; v2 = 20km/h

T= t1 + t2 = S/v1 + S/V2 = S/30 + S/20 = S/12

Average speed: V = S/T = 2S/T =2S x 12/S = 24km/h

speed=distance/time let x be distance total distance=2x total time=x/20 +x/30 avg speed =2* 20 * 30/50=24

This is good question. Shortcut is good for this like == Average speed= 2 (S1 S2)/(S1+S2) Where S1 and S2 are speeds of the body. Answer= 2 30 20/(30+20)= 24 km

avg speed = (2 × 20 × 30)/(20 + 30) = 24 shortcut formula = 2(s1 × s2)/(s1 + s2) wher s1 and s2 are speeds.

AVD SPEED=(2 * S1 * S2) / (S1 + S2)

=(2 * 30 * 20) / ( 30 + 20)

=24

average speed - 2 * u * v/(u+v)