# [SOLVED] acceleration question

• Sep 16th 2008, 07:05 AM
ally79
[SOLVED] acceleration question
In a 1500 metre race, runner A sets off at a constant speed of 5m/s Runner Bsets off 0 seconds later.

i) Calculate the speed at which runner B needs to run in order to finish equal first with runner A

ii) After 2 laps (800m) Runner A notices that B is catching up. Assuming that B is unable to increase his speed to respond how fast mut A run in order to win by 10 metres.

I worked out using v=s/t that runner B needs to run at 5.56m/s in order to finish equal first. Its the second question that i'm having problems with.

Initially i thought i had solved it using v=s/t again, but i realise that that is wrong because I cant just half the total time for A because it will be different now that he increases his velocity.

If someone can point me in the right direction that would be great
• Sep 16th 2008, 09:02 AM
Aryth
You sure that runner B sets off 0 seconds later?
• Sep 16th 2008, 09:04 AM
ally79
Aww Crap! My keyboard is rubbish, thats meant to be 30 secs later