# The Naked Scientists Forum

### Author Topic: Motion towards each other?  (Read 2483 times)

#### fortengc

• Jr. Member
• Posts: 11
##### Motion towards each other?
« on: 28/02/2011 08:58:57 »
1.)Jack and Tim were standing in the main street. The distance between the boys was x metres. At the same moment the boys started to move. Jack was running at a m/s and Tim walked at b m/s. Find the time when the boys met if
a) they moved towards each other,
b) they moved in the same direction, walker in front

Thanks plz hint me up on the solution

#### fortengc

• Jr. Member
• Posts: 11
##### Motion towards each other?
« Reply #1 on: 28/02/2011 09:00:29 »
2.)A train is going to Raahe and the velocity is 80 km/h. After half an hour another train leaves for Raahe and its velocity is 100 km/h. The trains arrive in Raahe at the same time. What is the length of the route?

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### Motion towards each other?
« Reply #2 on: 28/02/2011 09:18:04 »
This is not the place for us to answer your homework questions for you.  With earlier questions you have shown us that you understand the laws of motion so you should be able to answer these questions with few problems.  Both of these are best thought of as straight line graphical questions with the straight line graphs showing how far the people or trains have travelled in a given time.  These then lead to pairs of simultaneous equations (where they meet) which can then be solved algebraically.  for the second solution of the first question of course you have to assume that the runner runs faster than the walker walks!

#### syhprum

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##### Motion towards each other?
« Reply #3 on: 28/02/2011 15:23:41 »
Makes a nice change from blackholes and general relativity these simple arithmetic questions

#### fortengc

• Jr. Member
• Posts: 11
##### Motion towards each other?
« Reply #4 on: 28/02/2011 15:49:15 »
I used S= (u+v)/2*t for the first problem but still having probs.

#### syhprum

• Neilep Level Member
• Posts: 3765
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##### Motion towards each other?
« Reply #5 on: 28/02/2011 20:24:34 »
Here is a link to an interactive program for solving simultaneous equations

http://www.hellam.net/algebra/simul1.html

#### fortengc

• Jr. Member
• Posts: 11
##### Motion towards each other?
« Reply #6 on: 01/03/2011 02:48:21 »
Hello, its like we still don't get my problem ,its not how to solve the simultaneous equation that is above me.I am just a bit confused of how to form the equations.

#### yor_on

• Naked Science Forum GOD!
• Posts: 11651
• (Ah, yes:) *a table is always good to hide under*
##### Motion towards each other?
« Reply #7 on: 01/03/2011 11:40:18 »
Taken from the Internet, are they?
Shouldn't that make their answers obvious?

If you really want to impress your brilliance upon us, why not try your own instead, then we might become interested, at least you will make us smile. In the mean time, Try http://www.math.com/

#### Soul Surfer

• Neilep Level Member
• Posts: 3345
• keep banging the rocks together
##### Motion towards each other?
« Reply #8 on: 02/03/2011 00:27:06 »
The equation you quote is not really much use for this problem.

All the problems involve different bodies moving at constant velocities so if you drew a chart showing distance covered against time elapsed they would be straight lines.  Try drawing some simple graphs illustrating the three problems and you will see what is happening you need to find the solutions where the graphs meet.  You could fully solve the second problem graphically with a scale drawing but the first requires the graphs to be converted into equations and then  solved algebraically

#### yor_on

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• (Ah, yes:) *a table is always good to hide under*
##### Motion towards each other?
« Reply #9 on: 02/03/2011 13:26:39 »
Jack and Tim were standing in the main street. The distance between the boys was x metres.
At the same moment the boys started to move, Jack was running at a m/s and Tim walked at b m/s.
Find the time when the boys met if:
:
time = dist/speed
dist = x
:
a) they moved towards each other,
time =
:
b) they moved in the same direction, walker in front.
time =

Seriously, if this is a real question from your teacher you would do well to follow the link given by the images above. He seems to get them from 'conspicuous' sources?

#### The Naked Scientists Forum

##### Motion towards each other?
« Reply #9 on: 02/03/2011 13:26:39 »