Motion in a Straight Line - Result Question 30

31. A body starts from rest, what is the ratio of the distance travelled by the body during the 4th and 3rd seconds?

[1993]

(a) $\frac{7}{5}$

(b) $\frac{5}{7}$

(c) $\frac{7}{3}$

(d) $\frac{3}{7}$

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Answer:

Correct Answer: 31. (a)

Solution:

(a) $\frac{S_4}{S_3}=\frac{0+\frac{a}{2}(2 \times 4-1)}{0+\frac{a}{2}(2 \times 3-1)}=\frac{7}{5}$

Equation of the motion of uniformly accelerated motion, the distance travelled in $n^{\text{th }}$ sec is given by,

$ S_n=u+\frac{a}{2}(2 n-1) $