A person walking at a rate of 3km/hr, the rain falls vertically.when he increases his speed to 6km/hr it appears to meet him at an angle of 30 degrees.What is the speed of rain

Answers (1)
S safeer

Let the velocity of rain be xi + yj

Speed of the rain = \\\sqrt{x^2+y^2}\\\\

the velocity of man = 3i

The relative velocity between man and rain in case one is vertical

That is 

\\v_{rm}=(v_r-v_m)=(xi+yj)-3i\\

x=3 since relative velocity has only the vertical component.

Case 2

v_{rm}=(3i+yj)-6i=-3i+yj

Since the rain is coming at 30 degrees the angle between the relative velocity of rain and man is 150 degree

Therefore

\\\frac{y}{-3}=\frac{1}{\sqrt{3}}\\\\y=\sqrt{3}

Therefore

\\v_r=3i+\sqrt{3}j\\\\|v_r|=\sqrt{9+3}=\sqrt{12}=2\sqrt{3}m/s

Preparation Products

Knockout JEE Main April 2021 (One Month)

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 14000/- ₹ 4999/-
Buy Now
Knockout NEET Aug 2021 (One Month)

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 14000/- ₹ 4999/-
Buy Now
Knockout JEE Main May 2021

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 22999/- ₹ 9999/-
Buy Now
Knockout NEET Aug 2021

Personalized AI Tutor and Adaptive Time Table, Self Study Material, Weekend Live Classes, Mentorship from our Experts, Unlimited Mock Tests and Personalized Analysis Reports, 24x7 Doubt Chat Support,.

₹ 22999/- ₹ 9999/-
Buy Now
Test Series JEE Main May 2021

Unlimited Chapter Wise Tests, Unlimited Subject Wise Tests, Unlimited Full Mock Tests, Get Personalized Performance Analysis Report,.

₹ 6999/- ₹ 2999/-
Buy Now
Boost your Preparation for JEE Main with our Foundation Course
 
Exams
Articles
Questions