time/distance problem

• May 31st 2009, 06:18 PM
aashley
time/distance problem
yeah, i know people will tell me to do it myself and stop being lazy but i just can't figure it out! it's my last graduation requirement.

A large wildlife park is circular in shape and has a diameter of 7 miles.

Around the outskirts of the park is a circular train track. Two automatic trains travel around the park, both in a clockwise direction. The trains are designed to both average 20 mph so that they never meet. However, one train has developed a fault and now travels at 18 mph.

The trains set off from stations on opposite sides of the park at 9 a.m. At what time will the faster train catch up with the slower train?

and it asks these questions as well:

Where will the trains be when one catches up with the other?
How many times will each train pass its starting point before they meet?

When the faster train has caught up with the slower train, it changes direction. both trains are now traveling in opposite directions. After how many minutes will the trains meet again?

i am not asking for people to do it and give me the answers..i just really need help with this. it also says:
circumference = π x diameter. use π = 22/7

thank you!
• May 31st 2009, 06:54 PM
VonNemo19
Quote:

Originally Posted by aashley
yeah, i know people will tell me to do it myself and stop being lazy but i just can't figure it out! it's my last graduation requirement.

A large wildlife park is circular in shape and has a diameter of 7 miles.

Around the outskirts of the park is a circular train track. Two automatic trains travel around the park, both in a clockwise direction. The trains are designed to both average 20 mph so that they never meet. However, one train has developed a fault and now travels at 18 mph.

The trains set off from stations on opposite sides of the park at 9 a.m. At what time will the faster train catch up with the slower train?

and it asks these questions as well:

Where will the trains be when one catches up with the other?
How many times will each train pass its starting point before they meet?

When the faster train has caught up with the slower train, it changes direction. both trains are now traveling in opposite directions. After how many minutes will the trains meet again?

i am not asking for people to do it and give me the answers..i just really need help with this. it also says:
circumference = π x diameter. use π = 22/7

thank you!

The size of the track can be found by, $\displaystyle 2(7)\frac{22}{7}=2(22)=44$, and we know that if we chop this in half we'll know how far apart they are (22), and then we can forget about the circle because it no longer plays a part in the problem. Speed is speed.

O.K. Now we've gotta find at what time these two will meet. This is easy:

How much faster is the one train going than the other?

$\displaystyle 22-18=2$.

How long do you gotta ride at 2m/h before you go 22miles?

distance=rate*time, so

$\displaystyle 2t=22\Longleftrightarrow{t=\frac{22}{2}}\Longleftr ightarrow{t=11}$

Add 11 to 9 and waddayah git?(Wink) That'll be army time though...........
• May 31st 2009, 07:00 PM
aashley
Quote:

Originally Posted by VonNemo19
The size of the track can be found by, $\displaystyle 2(7)\frac{22}{7}=2(22)=44$, and we know that if we chop this in half we'll know how far apart they are (22), and then we can forget about the circle because it no longer plays a part in the problem. Speed is speed.

O.K. Now we've gotta find at what time these two will meet. This is easy:

How much faster is the one train going than the other?

$\displaystyle 22-18=2$.

How long do you gotta ride at 2m/h before you go 22miles?

distance=rate*time, so

$\displaystyle 2t=22\Longleftrightarrow{t=\frac{22}{2}}\Longleftr ightarrow{t=11}$

Add 11 to 9 and waddayah git?(Wink) That'll be army time though...........

ah, thank you so much! very helpful :)