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?
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
February 21st, 2009 16:15
no comments
April 23rd, 2009 19:16
I swear this formula doesn’t work for the following questions: 1) A car takes 15 minutes to travel 24 miles, find it’s speed in mph? i got 1.6mph, now that is obviously wrong. 2) A cyclist takes 10 minutes to travel 2.4 miles, calculate the average speed in mph? i got 0.24, now that is also obviously wrong, am i missing something here? Please get back to me before 10pm!!!
April 24th, 2009 09:52
Hi Will,
You made a vital mistake, using your first example.
24 / 15 is 1.6. But remember, that is in minutes, 1.6 miles a minute. You need to convert this to hours. 1.6 x 60 = 96. You can double check this by, 15 minutes is 0.25 of 1 hour. 24 / 0.25 = 96.
I hope this made things clearer for you, always look for which measurement the answer requires.
May 17th, 2009 14:51
Hey, i’m in year 11 and I have my Maths GCSE tomorrow. However, I always get stuck on these questions but I really want to crack them before tomorrow! I have a tutor, but I dont get the way he explains it to me, I just get confused so easily. I’m stuck on the following question.. “A runner runs 14 miles in 2 hours 20 minutes. Work out the speed…” How do I work out what 2 hours and 20 minutes is so I can work out the the speed? Please help!
May 17th, 2009 22:55
hey i have my maths exm 2moz too, i think its 14 divided by 140, 140 beacuse there are 140 minutes in 2 hours and 2o min
June 18th, 2009 10:37
holly - how did you go - mins in 2hours 20 is 140 minutes devided by 14 is 10 miles an hour
June 24th, 2009 17:20
Hi
i am fine when dealing with the easy calculations - but i find it hard when trying to work out questions such as ‘what speed covers 68 miles in 1 hour and 25 minutes?’
the time/minutes thing confuses me. i know the S=D/T triangle but this doesn’t seem to work and makes me more confused!
please help!
thanks
martin
June 25th, 2009 15:43
hi martin,
try first putting your time into hours, so it’ll be something like 1.42hours, then do
speed= distance / time
68 / 1.42
so speed = 48 mph
June 25th, 2009 19:06
is there a formula for changing to time in hours?
July 8th, 2009 06:51
Hi Ali, Molly, Martin, and anybody else who may be struggling -
You should keep your units the same. Here’s a quick example:
You travel 25 miles at 50MPH in ? time…
- use HOURS as your unit, since it’s miles per HOUR. Cover up the T in the triangle with your thumb - you’re left with D÷S. So 25÷50 is 0.5. That’s your time: 0.5 hours.
If you want, times the decimal by 60 to find the minutes. If you are given time in HOURS and MINUTES, instead of decimals, DIVIDE the minutes by 60 to get a decimal of the hour.
What I see some people struggling with is when conversion is brought into the picture too. Sometimes you may be presented with a question like “How long does it take to drive 35 miles at 80km/h”. If you are doing a paper, or have instructions it will usually tell you what unit your answer will have to be in. If not, convert one of the two so they are the same. Your answer will probably be a confusing number with endless decimals. If not told, make an educated guess to round your number. Three D.P. is usually a good idea.
So remember:
- Keep the units the same
- Work in a decimal timescale until the end.
July 23rd, 2009 18:16
hi
i have a problem that i want to throw out there
ok, “if you have to walk 1250ft and the speed that you are walking is
4 miles an hour
how long will it take to finish the 1250ft?”
i tried your formula and when i divided the speed, which is 4 mgh and the distance, which is 1250ft i got 312.5..
so is 312.5, minuits, hours or seconds???
September 21st, 2009 18:02
This confuses me. Here’s my question:
Janine walks at 6km/h for 1 hour 30 minutes then 4km/h for 2 hours 15 minutes. How far does she walk in total.?
Could you tell me how to work this out using the triangle please. =)
October 13th, 2009 20:57
do you always have to turn time into decimals and do yo do it by dividig the number by 60?
November 1st, 2009 21:57
Really good help, and some of the comment gave good advice as well! Thanks guys!
January 29th, 2010 08:04
this helped!!!!!!!!!!11 thanx….. So its:
Speed=Distance(DEVIDED by)Times
Distance=Times(MULTIPLY by)Speed
Times=Speed(DEVIDED BY)Distance
February 4th, 2010 13:57
This formula is really good just need to know how it works , it troubled me for ages.
so if you want to find the speed you traveled , a boat covers 16.2miles in 1 hour and 25 min.
speed = D/T
25/60 =0.41666 + ! = 1.41666
16.2 / 1.41666 = 11.435
So around 11.4 knots was the boats speed
So if a boat Traveled 11.4 knots for 1 hour and 25 min , how far did it travel ?
Distance = SxT
25/60 =0.41666 + 1
11.4 x 1.41666 = 16.149
So around 16.2 miles
If a boat traveled 16.2 miles at 11.4 knots how long would it take ?
Time = D/S
16.2/11.4 = 1.421 then - 1 = .421 x 60 = 25.26 then plus the 1 hour back on = 1 hour 25.26 min
So around 1 hour and 25 min
So each one id slightly different because of decimals i took of cause they were to far back.
Pretty good system i just learn t this today!!
February 6th, 2010 16:14
I will thank you very much for the smashing data about this topic! And you know, that the freelance writing would like to take that stuff at the term papers.
February 28th, 2010 13:07
jjjjjjjjjjjjjjjj
February 28th, 2010 13:12
this has helped me so much. i finally underastand english science equations. they kept getting things wrong though but they might be good at science just rubbish at english. very good if learning english, italian, finish, german, austrlien, austrian, american and irish.
April 2nd, 2010 14:23
If the speed is 20 m/s how many metres would sed person run if they had run for 93 mins
April 2nd, 2010 14:24
Also you are all very intelligent people…NOT
April 13th, 2010 09:53
Hello,
I have learnt this in maths but i still dont understand how this works , as i havs tried to use the formula triangle buh for some of the questions the answers seem to be wrong…. ??
Please can you teach me any other way of describing how to work out speed
thankss loveee
Takee Careeee
May 19th, 2010 14:38
Imporatant thing is not to mix up your units of measurement.
If the units you are provided in a question are metres and seconds then stick with them throughout the equation and convert them afterwards if necessary.
So if you have someone travelling 10m in 5s then it will be 10/5 metres per second.
You can then work out as metres per hour by multiplying the result by 3600 (or 60*60).
On the other hand if you are given a distance in metres and a speed in mph you are going to first have to convert the speed into metres per hour, or the distance into miles before you can work out the time taken.
so if distance is 100m and speed is 21mph as in an example above, you can’t just divide 100 by 21 since the units are different.
You would have to express the distance in miles or the speed in metres first.
so (roughly, using 1mile = 1560metres) it would look like this.
(d)0.0641(miles) / 21(mph) = 0.0031 (hour) ;
*60 (to get the number in mins) = 0.1831
*60 (to get the number in seconds) = 10.9890
so a person who can sprint 100metres at 21mph can do it in about 11 seconds, not too shabby.
June 4th, 2010 09:58
If Sam travels 11 miles in 15 mins, what is his average speed?
June 6th, 2010 16:26
I have looked through the posts and cant seem to get my head round it please advise!! If vessel has traveled 20 miles @12 knots D/T I seem to come up with 1.708333 how do i work out my time traveled with this?
June 17th, 2010 19:11
hello, i got a question and it has something to do with upper and lower bounds… i tried to do speed x time but i got the wrong answer here is the question…
A car travels at 50 mph for 4 hours and 15 minutes. What distance has it travelled?
Thank youu xx
August 9th, 2010 11:31
ok i am doing my math project and there is a trig question that requires me to use this formula. i used the formula (equation being 400km/h for 2hrs) and im not sure if i have to put my answer into kms or m.
pls help
and quick because this thing us due in on the 11th of aug…thanx
August 9th, 2010 12:24
@andy
its 1.7 hours…
August 17th, 2010 19:14
Any other thing but those three formulas of S, D and T I just don’t understand a shit…