Question

a car travels 30 km at a uniform speed of 40 km h and the next 30 km at a uniform speed of 20 kmh . find its average speed​

Answer 1

Answer:

26.67km/h

Explanation:

Avg speed=(total dist. /total time)

t1=(30/40)=0.75 h

t2=(30/20)=1.5 h

Avg speed=(30+30)/(1.5+0.75)=26.67 km/h

Answer 2

Answer = 26.67

It is given that a car travels 30km at the uniform speed of 40 km/hr and next 30 km at the speed of 20 km/hr.

We have to find the average speed of the car. Before finding the average speed, we will find the time taken by the car to cover the given distance.

We know the relation between distance speed and time is given by the formula

Distance = speed x time.

From this relation the time is being calculate d using the following formula,

Time= $\frac{distance}{speed} \\So, the time required by the car to cover 30km at the uniform speed of 40 km/hr is= \frac{30}{40} \\hours$

Again, the time required to cover the last 30 km at the uniform speed of 20 km/hr is $\frac{30}{20}$

So, from the found time we will calculate the total time,

30 300

The total time taken by the car is =$\frac{30}{40}$+$\frac{30}{20}$ hours

Let us simplify the above equation so that we get, the required time as $\frac{9}{4}$hours

Total distance is= 30 + 30 = 60 km

From the relation Distance= speed x time. we can say that

speed = $\frac{distance}{time}$

But substituting the known values we find the average speed, The average speed is $\frac{60}{9}$ km/hours

By simplifying the above term we get, the average speed is = 26.67 km/h

Hence, the average speed of the car is= 26.67 km/h

Note: We know that distance = speed x time is the primary relation between distance speed and time,