Motion In A Straight Line Ques 11
11. A particle starts its motion from rest under the action of a constant force. If the distance covered in first $10$ seconds is $S_1$ and that covered in the first $20$ seconds is $S_2$, then:
[2009]
(a) $S_2=3 S_1$
(b) $S_2=4 S_1$
(c) $S_2=S_1$
(d) $S_2=2 S_1$
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Answer:
Correct Answer: 11.(b)
Solution:
- (b) $u=0, t_1=10$ $ s, t_2=20 $ $s$
Using the relation, $S=u t+\frac{1}{2} a t^{2}$
Acceleration being the same in two cases,
$ \begin{aligned} & S_1=\frac{1}{2} a \times t_1^{2}, S_2=\frac{1}{2} a \times t_2^{2} \\ & \therefore \quad \frac{S_1}{S_2}=(\frac{t_1}{t_2})^{2}=(\frac{10}{20})^{2}=\frac{1}{4} \\ & \quad S_2=4 S_1 \end{aligned} $
BETA
