JEE Main 31-Aug-2021 Shift 2 Solved Paper

Let a block of mass M splits into two masses m1 and m2 in ratio 1: 2.
Then, mass of smaller part, m1=

M

1+2

=

M

3

Mass of bigger part, m2=2

M

3

Given, speed of mass M, v = 40 m/s
Speed of mass m1,v1=60m∕s
Let speed of mass m2,v2=v
Using conservation of linear momentum,
pi=pf
Mv=m1v1+m2v2
M×40=

M

3

×60+

2M

3

×v
⇒ = 30 m/s
∴ The fractional change in kinetic energy,

ΔK

K

=

Kf−Ki

Ki

=

Kf

Ki

−1
=

1 2 m1v12+ 1 2 m2v22

1 2 Mv2

−1