Question

You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h. your average speed over the 12 km drive will be

Answer 1

The average speed for the entire 12 km trip, with parts driven at different speeds, is approximately 64.3 km/h. This was calculated by summing the time taken for each segment of the journey and then dividing the total distance by the total time.

Step-by-step explanation:

To find the average speed for the total trip, we need to calculate the total distance traveled and the total time taken, and then divide the distance by the time.

First, calculate the time taken for each part of the trip:

• 
  
• For the first 6.0 km at 50 km/h:

Time = Distance ÷ Speed = 6.0 km ÷ 50 km/h = 0.12 hours

• 
  
• For the second 6.0 km at 90 km/h:

Time = Distance ÷ Speed = 6.0 km ÷ 90 km/h = 0.0667 hours

Add the times together to get the total time:

Total Time = 0.12 hours + 0.0667 hours = 0.1867 hours

Now, calculate the average speed:

Average Speed = Total Distance ÷ Total Time = 12 km ÷ 0.1867 hours = 64.3 km/h (approximately)

Therefore, the average speed over the 12 km drive is about 64.3 km/h.

Answer 2

v1=50km/h
v2=90km/h
s1=s2=6km
s=12km

The average speed over the 12 km drive:
v=s/t

The time needed to drive 12km will be:
t = t1+t2

t1=s1/v1, t2=s2/v2

t=s1/v1+s2/v2=(s1v2+s2v1)/(v1v2)

v=sv1v2/(s1v2+s2v1)=12*50*90/(6*50+6*90)=64,28 km/h