A vehicle was at rest. Suddenly it started moving. If the rate of increase in its acceleration in short interval of time is d t d a = 2 s e c 3 m
Then find its displacement from its starting point after 6 seconds of its motion.
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a=2t then v=t^2 then s=t^3/3 then integrate 0 to 6 s=72
G i v e n t h a t d t d a = 2 or, d a = 2 d t or, ∫ d a = ∫ 2 d t or, a = 2 t or, d t d v = 2 t or, d v = 2 t d t or, ∫ d v = ∫ 2 t d t or, v = t 2 or, d t d x = t 2 or, d x = t 2 d t or, ∫ d x = ∫ t 2 d t or, x = 3 t 3 n o w p l u g g i n g t h e l i m i t s 0 t o 6 w e g e t x = 3 6 3 - 3 0 3 x = 7 2
s o a n s w e r i s 7 2
Guys, there is a mistake in this question.its actually unsolvable without an initial condition for acceleration."initially at rest " simply implies v(t=0)=0 not a(t=0)=0.Therefor upon first integration we gets a=2t+C where C is a constant and finally S=(t^3)/3+C(t^2)/2.I solved it by assuming C=0.actually one more initial condition was needed.
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da/dt=2
da=2dt
integrating from 0 to t, we get
a=2t
dv/dt=2t (as a=dv/dt)
dv=2tdt
integrating
v=t*t
dx/dt=t*t (as v=dx/dt)
dx=t*t dt
integrating from o to t
x=(t * t * t)/3
when t=6
thus x= 72