Motion In A Straight Line Ques 51

51. If the velocity of a particle is $v=At+Bt^{2}$, where $A$ and $B$ are constants, then the distance travelled by it between $1$ $ s$ and $2 $ $s$ is :

(a) $\frac{3}{2} A+4 B$

(b) $3 A+7 B$

(c) $\frac{3}{2} A+\frac{7}{3} B$

(d) $\frac{A}{2}+\frac{B}{3}$

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Answer:

Correct Answer: 51.(c)

Solution:

  1. (c) Given : Velocity $v=At+Bt^{2}$

$\Rightarrow \frac{d x}{d t}=At+Bt^{2}$

By integrating we get distance travelled by the particle between $1$ $ s$ and $2 $ $s$,

$\Rightarrow \int_0^{x} d x=\int_1^{2}(A t+B t^{2}) d t$

$x=\frac{A}{2}(2^{2}-1^{2})+\frac{B}{3}(2^{3}-1^{3})=\frac{3 A}{2}+\frac{7 B}{3}$