Speed, distance and time
Distance travelled is equal to the speed times the time taken. So if you drive at an average speed of 30 mph for two and a half hours, you will travel 75 miles. There are three permutations of the formula,
- Distance = Speed x Time
- Time = Distance divided by Speed
- Speed = Distance divided by Time
The formula triangle is often used to help remember these relationships. Just put your finger over the letter you are trying to find, and the triangle tells you what calculation to do for the remaining two letters.
Suppose you want to know the time a journey will take. Cover up T and the triangle reveals D / S or distance divided by the speed you drive at as the required calculation.
September 19th, 2007 09:31
Hi,
this is all well with the formular but you have not mentioned whether you need to work the time out in hours, mins or seconds which can get confusing……for example take the formular above and lets say we are working out 1 mile and the time is 9 mins, working out the speed is wrong if you use the mins…D=1 T=9 so 1/9=0.11111, so this tells me i ran at 11.11mph but if you work out your example D=75 S=30 so 75/30=2.5, i know this means 150 mins, so do we have to convert the 9 mins into hours? if so that means i have to say T=9/60=0.15 so D=1 mile and T=0.15 so 1/0.15=6.66666 which is different to the previous calculation above, could you please shed some light on this?
Steve
September 19th, 2007 11:57
Hi Steve
Work in decimal hours always.
Convert minutes to decimal hours by dividing by 60 so 45 minutes is 45/60 = 0.75 hours.
January 23rd, 2008 10:42
hi
im trying 2 do mi maths home work and i dont get eny of this.. im only in year 8 so please could some one explain it more easily
molly
March 25th, 2008 20:39
hey molly
no worrys im only in 7th
try using the triangle, it really works!
the equations balow it help to
i dont know if this is the help u want but watevr
March 25th, 2008 20:55
Hello Ali and Molly
If you walk at 4 miles per hour, then in one hour you will go 4 miles, and in half an hour you will go 2 miles, and in two hours you will go 8 miles.
How far do you get in one and a half hours?
The key to this stuff (in my experience) is always to work in decimal hours. Don’t fiddle with minutes, conver them to decimal hours!
May 18th, 2008 15:07
Hello
I am confused on how to work out the speed?
do you keep it in minutes or hours?
May 18th, 2008 17:34
Always work in decimal hours if the question is asking about kilometres per hour or miles per hour. 2 hours and 30 minutes is 2.5 hours. 6 minutes is 0.1 of an hour.
May 22nd, 2008 21:26
no use or help
rubbbbbbbbbbbbbbbish
July 8th, 2008 10:55
Hi,
ummmmm I’m confused!! Ok I have this question: A train passes a telegraph post in 5 secs and a platform 60m long in 10secs. What r the speed and length of the train? HOW AM I SUPPOSED 2 FIGURE THAT OUT??
August 17th, 2008 09:34
ok ive been trying to work out how fast someone runs the 100m
i know that his sprint speed for the 100m is 21mph
using the triangle he can do the 100m in 4.75 secs. 100 divided by 21.
now since the record for the 100m was only broken yesterday with a time of 9.6 i think i’m doing something wrong. can somebody please help.
September 11th, 2008 07:23
I am think I get it but what about this?
If a hot air balloon takes off from a field and flys for twenty minutes (flying with the wind)with a wind speed of 5 knots
How do you work out distance traveled
Your speed
September 22nd, 2008 07:31
I am trying to work out if I travelled 1.5 kms in 1.2 minutes what speed would I be doing in kilometres per hour. Can anyone help.
September 29th, 2008 17:05
[…] The class started with a short worksheet of speed/distance/time problems, to prepare the kids for the kind of calculations they need to be able to do in the lab they were about to start. My CT drew the classic SDT triangle on the board, and then did something he rarely does - pulled out the candy for speedy/correct answers - a game he calls “speed hands”. […]
October 20th, 2008 18:44
how to work out the speed of a comet failing from the cround? ey can you tell me?
October 20th, 2008 18:44
how to work out the speed of a comet failing from the ground? ey can you tell me?
October 20th, 2008 18:45
duno i am a thicko
November 3rd, 2008 19:12
can sombody help me with me with this
i used the speed = distance divided by time but i keep getting the wrong answer.
this is what i did
i threw a ball 194cm at a time of 49 miliseconds when i worked it out on my calculator the way it said and ii got the answer 395.9183673469 what am i doing wrong
help plz