Math Is Fun Forum

LuisRodg

Real Member

Registered: 2007-10-23

Posts: 322

Is there enough information given?

A world-class sprinter accelerates to his maximum speed in 3.8 s. He then maintains this speed for the remainder of a 100m race, finishing with a total time of 9.3 s.

And then im asked what was his acceleration in the first 3.8secs? I dont seem to get it. It seems they are not giving enough info?

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Is there enough information given?

If a is his acceleration, then

and the distance he covers during this time is

He then runs the last 100−7.22a metres at his top speed in 9.3 − 3.8 = 5.5 seconds. Hence

Now you can solve for a.

Last edited by JaneFairfax (2008-02-09 08:19:16)

LuisRodg

Real Member

Registered: 2007-10-23

Posts: 322

Re: Is there enough information given?

If a is his acceleration, then

and the distance he covers during this time is

He then runs the last 100−7.22a metres at his top speed in 9.3 − 3.8 = 5.5 seconds. Hence

Now you can solve for a.

Very creative Jane. Dont think I could of thought of that.

Thanks

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: Is there enough information given?

Is the acceleration of a runner really linear?

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

LuisRodg

Real Member

Registered: 2007-10-23

Posts: 322

Re: Is there enough information given?

I forgot to say but the question asked for the average acceleration in the first 3.8 seconds.