Graphing Motion problem (motion in a straight line)

marienmn

1. The problem statement, all variables and given/known data
Karen lives 500 m from school travels to school in straight line.

Starts out at time zero at rest and accelereates towards school with an acceleration of 2.0 m/s2 for 10 seconds. she then travels at constant speed for 5 seconds.

she then slams on the brakes, coming to stop in 4 seconds.

she throws her car in reverse accelereating back home at 5 m/s2 for 3 seconds and then travelling at constant speed for 4 seconds. and then slowing at constant acceleration to stop back at home

she spends 20 seconds at home

then she accelerates at 8 m/s2 for 3 seconds then travels to within 50 m of the school (which is 450 m) and slows to a stop at constant acceleration.

QUESTION: Draw careful x-t,v-t and a-t graphs with all value calculated.



2. The attempt at a solution

I've attached an excel document of my attempt at it. I basically recored the time known as well as its position/velocity/ or accel that was given in the problem. I don't really know how to fil in the blanks tho, and i'm not even sure if my timings are right.

i also drew out the scenerio too but i can't scan it in.

Attached Files

graphing motion lab.xls (13.5 KB, 2 views)

marienmn

so i figured the first part out i don't need help with that but now i can't figure this out:

so i figured out that when she accelerates back home at 5m/s2 for 3 seconds she travels 22.5m at the end of those 3 seconds. then for the 4 seconds she travels at constant velocity that would be another 60m traveled, am i right? so in total it's 82.5m traveled which leaves for her another 157.5m to get back home. so i'm having problems with the "then slowing at constant acceleration to stop back at home," what formula would i use to find the time it takes for her to reach back home?

marienmn

guys dont bother solvin this i kinda figured it out thx tho