Question

A body starting from rest moves with constant acceleration. The ratio of distance covered by the body during the $5th$ sec to that covered in $5$ sec is :

• A. $9/25$
• B. $3/5$
• C. $25/9$
• D. $1/25$

Answer 1

Answer: (A)

$9/25$

Given,

$u=0m/s$

Distance covered by the $n^{th}$ sec,

$S=ut+a(n-\frac{1}{2})$

For $5^{th}$ sec

$S_1=0+a(5-0.5)$

$S_1=4.5a$. . . . . .. . . . .(1)

The distance covered by the body in 5 sec

$S_2=ut+\frac{1}{2}a{t}^2$

$S_2=0+\frac{1}{2}a\times 5\times 5$

$S_2=12.5a$. . . . . . . . .(2)

$\frac{S_1}{S_2}=\frac{4.5a}{12.5a}$

$\frac{S_1}{S_2}=\frac{9}{25}$

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