(27) A particle travels in a straight line. It covers 1st 5m distance with 2 different Velocities. For the 1st half of the time, it travel with 2mls and 4mls. For 2nd 5m it is travening with velocity 10m/s. Find the average velocity during the whole Journey.
Answers & Comments
Answer:
Let the total distance travelled be
′
d
′
. In the first part of journey, particle travels distance (d/2) with speed 5 m/s. So corresponding time, t
1
=
5
(d/2)
=
10
d
s.
Time of second and third part of journey is same, ⇒t
2
=t
3
Sum of distances of second and third parts is (d/2). Let the distance of second part of journey be
′
x
′
. Then,
6
x
=
4
(d/2)−x
[t
2
=t
3
]
⇒x=(3d/10)
t
2
=
6
x
=
10×6
3d
=(
20
d
)s=t
3
Total time of journey, t=t
1
+t
2
+t
3
⇒t=
10
d
+
20
d
+
20
d
=(
5
d
)s.
Average speed, V=
t
d
=
(d/5)
d
=5 m/s
Option (D) is the correct answer.
Explanation: