Warning

 

Close
Confirm Action

Are you sure you wish to do this?

Cancel Confirm
AR15.COM
8/30/2013 7:18:58 AM EDT
One of my friends is bugging me with this, I thought I had it right but they say no.

Bus 1 leaves the station at 12:00pm at 62mph. Bus 2 leaves 4 hours later following the same path traveling at 77mph. When will bus 2 overtake 1, assume it is a straight road with no stops or anything and instant acceleration.

I came up with 4:32 in the morning the following day
8/30/2013 7:22:48 AM EDT
[#1]
I get 8:32 AM.  The closing of the gap starts at 4 PM when the second bus leaves.  At that time the first bus is 248 miles ahead



With a 15 MPH differential that works out to 992 minutes to catch up, or 16 hrs. 32 min.



 
8/30/2013 7:25:18 AM EDT
[#2]
I got 20 hours 32 minutes from the time the first train left, so 8:32 am.

Rate x Time = Distance

Train 1: 62 mph x t hours = m miles
Train 2: 77 mph x (t - 4) hours = m miles

Set them equal and solve for t.
8/30/2013 7:28:21 AM EDT
[#3]
Quote History
Quoted:
I got 20 hours 32 minutes from the time the first train left, so 8:32 am.

Rate x Time = Distance

Train 1: 62 mph x t hours = m miles
Train 2: 77 mph x (t - 4) hours = m miles

Set them equal and solve for t.
View Quote


WinnahWinnahChickenDinnah
8/30/2013 7:29:46 AM EDT
[#4]
yep I was on the right path I just forgot to take into account the 4 hour difference in departure times. Thanks
8/30/2013 7:33:43 AM EDT
[#5]

Quote History
Quoted:


yep I was on the right path I just forgot to take into account the 4 hour difference in departure times. Thanks
View Quote


Let's hope that the driver of bus #2 isn't texting.







 
8/30/2013 7:34:46 AM EDT
[#6]
B1: 12pm @ V2=62mph
B2: 4pm @ V1=77mph

X1=V1*t
X2= V2*t-V2*4(hours)

solve X1=X2 for t

t= (V2*4) / (V2-V1)

t=20.53 or 8:32am the nest morning


ETA: Beat to the punch...
8/30/2013 7:49:48 AM EDT
[#7]
Entirely too pleased with myself for getting this answer right.

8/30/2013 7:54:17 AM EDT
[#8]
Doesn't matter.  With instant acceleration everyone would be dead and the universe would cease to exist with the energy used to do this.
8/30/2013 8:04:25 AM EDT
[#9]
Bus 2 is struck in traffic for 8 hours due to a 20 car pile up involving 4 tractor trailers that over turned and caught fire.

Therefore bus 2 never catches up to bus 1 which left at 4am on its way to Vegas.  

Or the correct answer is 87
8/30/2013 8:06:38 AM EDT
[#10]
Is either of the buses on a treadmill?


8/30/2013 8:20:07 AM EDT
[#11]
Quote History
Quoted:
Doesn't matter.  With instant acceleration everyone would be dead and the universe would cease to exist with the energy used to do this.
View Quote

Never heard of a rolling start?  
Close Join Our Mail List to Stay Up To Date! Win a FREE Membership!

Sign up for the ARFCOM weekly newsletter and be entered to win a free ARFCOM membership. One new winner* is announced every week!

You will receive an email every Friday morning featuring the latest chatter from the hottest topics, breaking news surrounding legislation, as well as exclusive deals only available to ARFCOM email subscribers.


By signing up you agree to our User Agreement. *Must have a registered ARFCOM account to win.