[jenny_02912]

I have a test coming up and I keep messing up on average velocity :(

[Yusf]

Hello!
The average velocity (v) is found dividing distance by speed. The best way to remember this is by the unit of velocity. V is manytimes measured by km/hr. (kilometre per hour. We say car travels at 50 km/hr.) Here '/' denotes divide. That's it. The formula is also km/hr or km ÷ hr or figure in km ÷ figure given in hr or distance ÷ time.

In exams you only need to show v=d÷t.

PS acknowledge if this helps or not.

[ebaines]

I would add that you should always remember that average speed is the total distance travelled divided by the total time taken. Often in homework and exams they will try to fool you into giving the wrong answer by making it seem you can simply take the average of speeds for different segments, but that's incorrect.

Here's an example of a typical question: if a car travels at 60 MPH for 60 miles and then 30 MPH for 60 miles, what's the average speed? At first glance it may be tempting to simply average 60 MPH and 30 MPH to get 45 MPH, but that is incorrect. The proper way to solve this is to find the total distance travelled (in this case 120 miles) and divide by the total time taken. Here it takes 1 hour for the first segment (60 miles/60 MPH = 1 hour) and two hours for the second segment (60 miles/30 MPH = 2 hours). Thus the total time is 3 hours, and the average speed is 120 miles/3 hours = 40 MPH. Note that this is different than simply averaging the two speeds. If you remember to always use total distance and total time when calculating average speed you'll do fine.