Work Energy And Power Question 134

Question: A mass ’m’ moves with a velocity ‘v’ and collides inelastically with another identical mass. After collision the Ist mass moves with velocity v3 in a direction perpendicular to the initial direction of motion. Find the speed of the 2nd mass after collision [AIEEE 2005]

Options:

A) 23v

B) v3

C) v

D) 3v

Show Answer

Answer:

Correct Answer: A

Solution:

Let mass A moves with velocity v and collides in elastically with mass B, which is at rest.

According to problem mass A moves in a perpendicular direction and let the mass B moves at angle q with the horizontal with velocity v.

Initial horizontal momentum of system (before collision) = mv ….(i)

Final horizontal momentum of system (after collision)   =mVcosθ ….(ii)

From the conservation of horizontal linear momentum mv = mV cosq therefore v = V cosq …(iii)

Initial vertical momentum of system (before collision) is zero.

Final vertical momentum of system mv3mVsinθ

From the conservation of vertical linear momentum mv3mVsinθ=0 therefore v3=Vsinθ …(iv) By solving (iii) and (iv) v2+v23=V2(sin2θ+cos2θ)

therefore 4v23=V2

therefore V=23v .



NCERT Chapter Video Solution

Dual Pane