How was v2025t aquired GROUP PROBLEM SOLVING I continued Now

How was v=20-.25t aquired?

GROUP PROBLEM SOLVING I (continued) Now find the distance traveled Aso J v dt 10 dt 10 (40) 400 m 0-40 AS40-80 (20 0.25 t) dt 20 t-0.25 (1/2) 200 m So oo 400 200 600 m /s) vavg(0-90) total distance/ time 600 80 r (s) 7.5 m/s ALWAYS LEARNING Dynamics, Fourteenth Edition Copyright 2016 by Pearson Education, Inc. PEARSON All rights R-C Hibbeler

Solution

he given wrong in place of 10 given 20 please make it 10 and you will get same answer

now at time t=0 velocity is 10 m/s there is no accelaration up to 40 sec

v remains 10m/s

then next car undergo decelaration and come to rest

V=U+at

0=10+(-a)*(80-40)

a=-0.25 m/s^2 -ve sign indicates decelaration

next he wants to find distance

put V=10-.25t

and integtrate as same in question u will get same answer