Posttion of an object moving along x -axis ts given by x=a+b t^{2} where a=8.5 mathrm{m}, b=2.5 math

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2.Motion in Straight Line

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The posttion of an object moving along $x$ -axis ts given by $x=a+b t^{2}$ where $a=8.5\; \mathrm{m}, b=2.5 \;\mathrm{m} \mathrm{s}^{-2}$ and $t$ is measured in seconds. What is the average velocity between $t=2.0 \;\mathrm{s}$ and $t=4.0 \;\mathrm{s} ?$

A

$20 \;\mathrm{ms}^{-1}$

B

$10 \;\mathrm{ms}^{-1}$

C

$25 \;\mathrm{ms}^{-1}$

D

$15 \;\mathrm{ms}^{-1}$

Solution

$\text { Average veloctty } =\frac{x(4.0)-x(2.0)}{4.0-2.0}$

$=\frac{a+16 b-a-4 b}{2.0}=6.0 \times b$

$=6.0 \times 2.5=15 \mathrm{ms}^{-1}$

Standard 11

Physics

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