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

Two bodies of masses m1 and m2 are initially at rest at an infinite distance apart. They are then allowed to move towards each other under mutual gravitational attraction. Their relative velocity of approach at a separation distance r between them is

A
[2G(m1m2)r]1/2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
[2Gr(m1+m2)]1/2
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
C
[r2G(m1m2)]1/2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
D
[2Grm1m2]1/2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is B [2Gr(m1+m2)]1/2

(When allowed to move towards each other)
Let velocities of these masses at r distance from each other be v1 and v2 respectively.
By conservation of momentum
m1v1m2v2=0m1v1=m2v2 ... (i)
By conservation of energy
Decrease in P.E.=Increase in K.E.
Gm1m2r=12m1v21+12m2v22 ... (ii)
On solving equation (i) and (ii)
v1=2Gm22r(m1+m2) and v2=2Gm21r(m1+m2)
vapp=|v1|+|v2|=2Gr(m1+m2)

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Gravitational Potential Energy
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon