Book Online Demo

Check Your IQ

Try Test

Courses

Dropper NEET Course Dropper JEE Course Class - 12 NEET Course Class - 12 JEE Course Class - 11 NEET Course Class - 11 JEE Course Class - 10 Foundation NEET Course Class - 10 Foundation JEE Course Class - 10 CBSE Course Class - 9 Foundation NEET Course Class - 9 Foundation JEE Course Class -9 CBSE Course Class - 8 CBSE Course Class - 7 CBSE Course Class - 6 CBSE Course

Offline Centres

Q.

A spherical rain drop evaporates at a rate proportional to its surface area at that instant. The radius of the drop initially is 3mm and after one hour it is found to be 2mm if r(t) represents radius of the drop at time ‘t’. then

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away

An Intiative by Sri Chaitanya

a

$r (t) = 3 + t^{3} - 2 t$

b

$r (t) = 3 - t^{3}$

c

$r (t) = 3 + t^{2} - 2 t$

d

$r (t) = 3 - t$

answer is A.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

We have, $\frac{d v}{d t} = λ .4 π r^{2}$
$\Rightarrow \frac{d (\frac{4}{3} π r^{3})}{d t} = λ .4 π r^{2}$
$\Rightarrow 4 π r^{2} . \frac{d r}{d t} = λ .4 π r^{2}$
$\Rightarrow \frac{d r}{d t} = λ \Rightarrow r = λ t + c_{1}$
We have, $r_{0} = 3$ and r=2 at t=1
$\Rightarrow c = 3, 2 = λ + 3 \Rightarrow λ = - 1 \Rightarrow r = 3 - t$

Watch 3-min video & get full concept clarity

Related Blogs

Get ₹ 1 crore* worth scholarship for JEE / NEET / Foundation

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Online Course for IIT JEE

Best Online Course for NEET

Best Online Course for CBSE

Best Courses for You

JEE

JEE

NEET

NEET

Foundation JEE

Foundation JEE

Foundation NEET

Foundation NEET

CBSE

CBSE

Get Expert Academic Guidance – Connect with a Counselor Today!

Related Blogs

Get ₹ 1 crore* worth scholarship for JEE / NEET / Foundation

Result Producing online coaching for JEE/NEET of south India

Largest All India Test Series for JEE/NEET

Best Online Course for IIT JEE

Best Online Course for NEET

Best Online Course for CBSE

Not sure what to do in the future? Don’t worry! We have a FREE career guidance session just for you!