Velocity of a particle

[john3j]

Hello,
I was hoping that someone could help me figure out what exactly I am supposed to do in the following problem.

A particle moving in a straight line is at a distance of s(t)=2.5t^2+18t feet from its starting point after t seconds where .

a. Find the velocity at t=6
b. Find the velocity at t=9

So would I just plug in 6 and 9 for t? I am not sure what to do about the 0<=t<=12 part. Is this just extra data that is not needed? I appreciate any clarification!

Thanks,
John

 

[wjm11]

Hello,
I was hoping that someone could help me figure out what exactly I am supposed to do in the following problem.

A particle moving in a straight line is at a distance of s(t)=2.5t^2+18t feet from its starting point after t seconds where .

a. Find the velocity at t=6
b. Find the velocity at t=9

So would I just plug in 6 and 9 for t? I am not sure what to do about the 0<=t<=12 part. Is this just extra data that is not needed? I appreciate any clarification!

Thanks,
John

s(t)=2.5t^2+18t is the DISPLACEMENT function, not the velocity function. Velocity = ds/dt. You need to take the derivative of the displacement function to find the velocity function.