Calculating Speed

Speed = Distance / Time

This is fairly straight forward. If you are given a distance (km, m, or some ridiculous unit such as miles) and a time (hr, min, sec); you simply divide the distance by the time. The unit for speed would be km/hr, m/s, or something similar (we here mph very often which is miles/hr).

Trying to determine how far an object will travel and how long a trip will take can be simple as well. You could do a little algebra and rearrange your variables or you can remember our simple triangle.











We glued one into our notebooks! The triangle will give you the equation you need if you simply cover up the measurement you are looking for. Looking for the distance? Cover up the D and you get Speed x Time, so D = S x T. Time? Cover up the T for Distance / Speed or T = D / S!

Example:

1. Ms. Walls is running away from zombies at 3 m/s. If safety is 60 m away, how long will it take Ms. Walls to reach safety? Since we are looking for a time, our equation is  T=D/S, now we fill in the information we are given.
• T = 60 m / 3 m/s (since we have m on top and m on bottom, our unit cancel and we have s)
• T = 20 s
• Does this make sense? Double check your number and units! 

Always pay attention to the units you are given and the units you are asked to give your answer in.

1. Snoopy has flown his doghouse 15 km and it has taken him 30 min. What is his speed in km/hr? The easiest way to solve this is to convert 30 min to hr. Since there are 60 min/hr; divide 30 min by 60 min/hr to get 0.5 hr. Then, find the speed. S=D/T, so S= 15 km / 0.5 hr = 30 km/hr.