# Kinematic Equations

7yler
A person runs 100 m in 9.77 s. Maximum speed was reached in 3 s, then maintained for the rest of the time. What was the acceleration during the first 3 seconds?

I know that I can find the average velocity, which is 100 m/9.77 s, and i know that initial velocity is 0 m/s. I don't know how to find the acceleration because I don't know what the velocity is. Could anyone guide me through the methodology of this problem? I don't want the numerical answer.

nikhil khatri
it can be like this.
initial velocity=0
velocity at the end of 3 sec is100/9.77m/s i.e. 10.23m/s
now acc. = (final vel. - initial vel.)/time=(10.23-0)/3=3.41m/sec.sq
so,acc. after 3 sec is 3.41m/sec.sq

7yler
The system is telling me that that is incorrect.

Homework Helper
Find the displacement and velocity at 3 seconds. Find the displacement and velocity at 9.77 seconds.

7yler
How do I find displacement and velocity if I don't know acceleration?

Homework Helper
I meant, find equations for them (the equations will contain "a").

7yler
I don't understand how I can solve the equations with two missing variables.