What is the average speed of an object that is still at t=0t=0 and accelerates at a rate of a(t) = 6-ta(t)=6t from t in [0, 2]t[0,2]?

1 Answer
Mar 18, 2016

v_a=8,5 " "m/sva=8,5 ms

Explanation:

1-"find v(t) function"1find v(t) function
v(t)=int a(t) d t=int (6-t)d t=6t-1/2t^2+Cv(t)=a(t)dt=(6t)dt=6t12t2+C
"for t=0 v=0 C=0"for t=0 v=0 C=0
v(t)=6t-1/2t^2+0v(t)=6t12t2+0
2-"find displacement between t=0 and t=2"2find displacement between t=0 and t=2
Delta x=int _0^2 v(t) d t

Delta x=int _0^2 (6t-1/2t^2)d t=|6*1/2 t^2-1/2*1/3*t^3|_0^2

Delta x=(3*2^2-1/6*2^2)-(0-0)
Delta x=12-4/6=(72-4)/6=68/4=17
3-"find "v_a=(Delta x)/(Delta t)

v_a=17/(2-0)
v_a=17/2

v_a=8,5 " "m/s