Question

The speed of a motor launch with respect to still water = 7 ms-1 and the speed of stream is u = 3 ms
When the launch began travelling upstream, a float was
dropped from it. The launch travelled 4.2 km upstream,
turned about and caught up with the float. How long is it
before the launch reaches the float ? plss tell as soon as possible with explanation ​and no spammers please​

Answer 1

Answer:

Speed of the boat when it travels upstream = 7-3 = 4 m/sec

Speed of the boat when it travels downstream = 7+3 = 10 m/sec

Now,

As soon as the float falls , it will travel downstream at the speed of 3 m/sec

And in the meantime, boat has also traveled upstream a distance of 4.2 km

So,

Time spend on travelling upstream by the boat = 4200/4

=1050 sec

In the meantime the float would had traveled downstream by,

=1050×3

=3150 m

Hence, the total distance between the float and the boat will be

=3150 + 4200

=7350 m

Now, the relative speed between boat and the float

=10-3

=4 m/sec

Hence time taken = 7350/4

=1837.5 sec

Hence, total time spent = 1837.5+1050

=2887.5 sec

This is 2887.5 /60

= 48.125 mins

Hence the float and the boat will meet in 48.125 mins

Explanation:

hope it helps mrk me as BRAINLIEST

Answer 2

48.12 is the answer as we should put digits upto 2 places of decimal. Thanks❣✌