can someone check my work please thanks, oh btw Im still trying to learn how to use LaTeX mathematical typesetting; I figured itll be slightly faster taking a picture of the problem and my work and posting it here so please bare with me(adsbygoogle = window.adsbygoogle || []).push({});

1. The position of a toy locamotive moving on a straight track along the x-axis is given by the equation x = t^3 - 6t^2 + 9t, where x is in meters and t is in seconds. The net force on the locomotive is equal to 0 when t is equal to (a) zero (b) 2s (c) 3s (d) 4s (e) 5s

(my work)

x = t^3 - 6t^2 + 9t

v = 3t^2 - 12t -- first derivative

a = 6t - 12 -- second derivative

0 = 6t - 12

12 = 6t

t = 2s

Question 2: http://ourworld.cs.com/LezardV4leth/problem_2.jpg [Broken]

Work: http://ourworld.cs.com/LezardV4leth/problem_2_work.jpg [Broken]

Question 3: http://ourworld.cs.com/LezardV4leth/problem_3.jpg [Broken]

Work: http://ourworld.cs.com/LezardV4leth/problem_3_work.jpg [Broken]

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Energy problems/work check

**Physics Forums | Science Articles, Homework Help, Discussion**