106@che: dont think b is true .. check again..
(d) is also true naa?
Q. The position vector of a particle is given by the relation \vec{r} = \vec{\alpha }(1-\gamma t+\beta t^{2}), where \vec{\alpha } is a constant vector while \beta and \gamma are positive constants. Which of the following statements is true?
(a) Velocity at t=0 is -\gamma \vec{\alpha }
(b) displacement in the first two seconds is \vec{\alpha }(1-2\gamma +4\beta )
(c) Acceleration at t=0 is 2\beta \vec{\alpha }
(d) speed is decreasing with time at t=0
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7 Answers
106
1acceleration positive at t=0 so speed is increasing at t=0
ya b is not correct..agree with u
1yes asish....me gettin...abd...
b> says displacement not distance......
106@che. acceleration positive.. direction of vel. is negative... so it serves as to decrease the speed naa?
position at t=2 is what is given in (b)
It is asking displacement.. which is r(2) - r(0)
1a=d2r/dt2 >0 at t=0
so v=dr/dt is an increasing at t=0
hence v is increaing at t=0
so speed is increasing
am i rong with it?
