Motion In A Straight Line Ques 48
48. A bus travelling the first one third distance at a speed of $10$ $ km / h$, the next one third at $20$ $ km /$ $h$ and the last one-third at $60 $ $km / h$. The average speed of the bus is
[1991]
(a) $9 $ $km / h$
(b) $16 $ $km / h$
(c) $18 $ $km / h$
(d) $48 $ $km / h$
Show Answer
Answer:
Correct Answer: 48.(c)
Solution:
- (c) Average speed $=\frac{s}{\frac{s}{3} \cdot \frac{1}{10}+\frac{s}{3} \cdot \frac{1}{20}+\frac{s}{3} \cdot \frac{1}{60}}$
$ =\frac{s}{s / 18}=18 $ $km / h $
In case speed is continuously changing with time, then, $Vav=\frac{\int v d t}{\int d t}$
BETA
