- #1
Satvik Pandey
- 591
- 12
Homework Statement
A dog sees a rabbit running in a straight line across an open field and gives chase. In a rectangular coordinate system (L,0), assume:
(i) The rabbit is at the origin and the dog is at the point at the instant the dog first sees the rabbit.
(ii) The rabbit runs up the y-axis and the dog always runs straight for the rabbit.
(iii) The dog runs at twice the speed of the rabbit.
Assuming L=300 units, how much does the dog have to travel to catch the rabbit?
Enter your answer as the distance the dog has traveled from sight to meal.
Homework Equations
The Attempt at a Solution
From the figure
in vertical direction
##-dx=(2v-vcos\theta )dt##
##\int _{ 300 }^{ 0 }{ -dx } =\int _{ 0 }^{ t }{ (2v-vcos\theta )dt } ##
##300=2vt-v\int _{ 0 }^{ t }{ (cos\theta )dt } ##......(1)
in horizontal direction
##vt=2v\int _{ 0 }^{ t }{ (cos\theta )dt } ##
##\int _{ 0 }^{ t }{ (cos\theta )dt } =\frac { t }{ 2 } ##
putting this value in eq (1)
##300=2vt-\frac { vt }{ 2 } ##
##t=\frac { 200 }{ v } ##
I think we have to find displacement of dog.
Distance traveled by rabbit in this time is 200
By pytha
Displacement should be ##\sqrt { 40000+90000 } =360.55##
But this is incorrect.
Where did I go wrong.