A car drives north on highway at 40km/h and then turns back and drives south back to the strating point at 60 km/h, what is the avarge speed of the car?
Tn = d / 40
Ts = d / 60
Save = 2d / (5d / 120)
i didn't get it
To find the average speed, we need to consider the total distance traveled and the total time taken by the car.
Let's break down the situation. The car initially travels north at 40 km/h, and let's say it travels for a distance of "d" kilometers. Since we know that speed is equal to distance divided by time, we can write the equation as:
40 km/h = d/t1 Equation 1
Next, the car turns back and drives south at 60 km/h. It travels the same distance "d" back to the starting point. Now, the time taken can be represented as:
60 km/h = d/t2 Equation 2
To calculate the average speed, we need to consider the total distance traveled and the total time taken. In this case, the total distance traveled is 2d (since the car goes north and then comes back to the starting point), and the total time is the sum of t1 and t2.
Total distance traveled = 2d
Total time taken = t1 + t2
Now, let's solve Equation 1 for t1:
t1 = d/40 km/h
Similarly, let's solve Equation 2 for t2:
t2 = d/60 km/h
Substituting the values of t1 and t2 in the equation for the total time taken:
Total time taken = d/40 km/h + d/60 km/h
To simplify the equation, we can find a common denominator:
Total time taken = (3d + 2d) / (120 km/h)
Total time taken = 5d / 120 km/h
Now, substitute the values of the total distance traveled and the total time taken into the average speed formula:
Average speed = Total distance traveled / Total time taken
Average speed = 2d / (5d / 120 km/h)
Simplify the expression:
Average speed = (2d) * (120 km/h/5d)
Average speed = (2 * 120 km/h) / 5
Average speed = 240 km/h / 5
Average speed = 48 km/h
Therefore, the average speed of the car is 48 km/h.