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#1 2010-03-20 17:21:51
- soha
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- Registered: 2006-07-07
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Speed
If a vehicle increases its speed by 2km/h to its initial speed, it will take half an hour less to travel a
distance of 240km. Find its speed.
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#2 2010-03-20 18:08:53
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
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Re: Speed
Hi soha;
It's velocity is:
Woops, sorry soha. Didn't read the problem correctly. thought it was 1 hour difference instead of 1 / 2 . Ignore this answer.
Last edited by bobbym (2010-03-21 09:50:42)
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#3 2010-03-21 02:46:11
- soha
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Re: Speed
481?????
I did'nt understand
"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay
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#4 2010-03-21 03:34:37
- soroban
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Re: Speed
. .
. .
.
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#5 2010-03-21 03:48:27
- soha
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Re: Speed
I did'nt understand why you multiplied by 2s(s+2),, and the following steps;
Please explain why you did it ??
"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay
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#6 2010-03-21 11:02:25
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Speed
Hi soha;
Soroban has answered the question correctly. Here is my correction from post #2 where I used 1 hour instead of 1/2 hour. Looks like I need more practice than you do, so I did it again.
Using d = v * t you get:
Expand the RHS:
Solve for t in the first equation:
Substitute for t
Solve for v:
v = 30, v = - 32
We reject v = -32, so v = 30 km / h
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#7 2010-03-21 18:57:46
- soha
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- Registered: 2006-07-07
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Re: Speed
if we use the equation time=distance/speed , and the speed as x
we get,
first time=240/x
after increaing the speed, time= 240/x+2
240/x - 240/x + 2 = 1/2
I got the answer by this way
Can we solve it by this way ?? Is this method correct??
Last edited by soha (2010-03-21 19:00:23)
"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay
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#8 2010-03-21 20:56:10
- ZHero
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Re: Speed
yeah ... u can!!!
If two or more thoughts intersect, there has to be a point!
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#9 2010-03-21 21:00:59
- soha
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- Registered: 2006-07-07
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Re: Speed
thats good then
"Let us realize that: the privilege to work is a gift, the power to work is a blessing, the love of work is success!"
- David O. McKay
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