SOLUTION: respected sir, 1] A hare sees a dog 100 metres away from her,& scuds off in the opposite direction at a speed of 12 km an hour.A minute later the dog perceives her & gives chase

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: respected sir, 1] A hare sees a dog 100 metres away from her,& scuds off in the opposite direction at a speed of 12 km an hour.A minute later the dog perceives her & gives chase      Log On

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Question 195768: respected sir,
1] A hare sees a dog 100 metres away from her,& scuds off in the opposite direction at a speed of 12 km an hour.A minute later the dog perceives her & gives chase at a speed of 16 km per hour.How soon will the dog overtake the hare ,& at what distance from the spot whence the hare took flight ?
2] A carriage driving in a fog passed a man who was walking at the rate of 3 km an hour in the same direction.He could see the carriage for 4 min.& it was visible to him upto a distance of 100 m. what was the speed of the carriage ?
plz explain me this sums...waiting for yurs reply.
thank u.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
The equations for both hare and dog are:
d%5Bh%5D+=+r%5Bh%5D%2At%5Bh%5D
and
d%5Bd%5D+=+r%5Bd%5D%2At%5Bd%5D
These are laws of constant speed motion, and
the key to not getting confused is to only
apply them when the hare and dog are moving.
I would like to have them both moving from
start to finish, but how do I do that?
I have a stopwatch and I will start it
when the dog starts running. But where is the hare
then? The hare has a 1 minute headstart, and
in that time, she goes
d%5Bh%5D+=+12%2A%281%2F60%29
d%5Bh%5D+=+.2 km
I start my stopwatch and stop it when the dog
catches the hare
d%5Bh%5D+=+r%5Bh%5D%2At%5Bh%5D
d%5Bh%5D+=+12t%5Bh%5D
The dog has to make up 100 m plus 200 m
d%5Bd%5D+=+d%5Bh%5D+%2B+.3 km
d%5Bh%5D+%2B+.3+=+16%2At%5Bd%5D
The dog's time and the hare's time will now be the
same on my stopwatch, so I'll say they both are t
d%5Bh%5D+%2B+.3+=+16t
(1) d%5Bh%5D+=+16t+-+.3
and
(2) d%5Bh%5D+=+12t
Subtract (2) from (1)
(1) d%5Bh%5D+=+16t+-+.3
(2) -d%5Bh%5D+=+-12t
0+=+4t+-+.3
4t+=+.3
t+=+.075 hr
t+=+.075%2A60 min
t+=+4.5 min
It takes the dog 4.5 min to overtake the hare
How far does the hare go in that time?
(1) d%5Bh%5D+=+16t+-+.3
d%5Bh%5D+=+16%2A.075+-+.3
d%5Bh%5D+=+1.2+-+.3
d%5Bh%5D+=+.9 km
But the hare is already 200 m from her starting point, so
The dog overtakes the hare at
.9+%2B+.2+=+1.1 km
1100 m from the hare's starting point
check answer:
The dog has to go
.1+%2B+1.1+=+1.2 km in .075 hr to catch the hare
d%5Bd%5D+=+16%2At
1.2+=+16%2A.075
1.2+=+1.2
OK
I don't have time for the other question, sorry