wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

Two drops of same radius are falling through air with a steady velocity of 5 cm/s. If the two drops coalesce, the terminal velocity will be

A
10 cm/s
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
2.5 cm/s
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
5×(4)1/3 cm/s
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
5×2 cm/s
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C 5×(4)1/3 cm/s
Terminal velocity for a spherical body of radius R and density ρ falling in a liquid of density σ and dynamic viscosity η is given by,
VT=29(ρσ)R2gη
VTR2
Let two identical drops of radius R1 coalesce to form bigger drop of radius R2,
VT2VT1=R22R21(1)
Since the volume remains same before and after the drops coalesce. Therefore,
Vi=Vf
2×43πR31=43πR32
R2=(2)1/3R1
Substituting this in equation (1),
VT2VT1=(4)1/3R21R21
VT2=5×(4)1/3 cm/s

flag
Suggest Corrections
thumbs-up
1
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Viscosity
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon