How to find instantaneous velocity at t = 3.5 s for a race car

[Rymac]

This problem seems simple enough, I guess I just don't really understand what it's looking for in the (b) portion.

A race car moves such that its position fits the relationship where x is measured in meters and t in seconds.
x = (5.0 m/s)t + (0.80 m/s³)t³

(a) Plot a graph of the car's position versus time. (Do this on paper. Your instructor may ask you to turn in this work.)

(b) Determine the instantaneous velocity of the car at t = 3.5 s, using time intervals of 0.40 s, 0.20 s, and 0.10 s.

Δt = 0.40 s ____________m/s

Δt = 0.20 s ____________m/s

Δt = 0.10 s ____________m/s


(c) Compare the average velocity during the first 3.5 s with the results of (d).
The average velocity of _14.8_ m/s is (*d1*) much less than (d2) about the same as (d3) much greater than the instantaneous velocity.

 

[Integral]

You need to show that you have but some kind of thought into this problem.

what is your definition of Average and instanenous velocity?