EAMCET Engineering 2009 Solved Paper

Mass of the first body m1=5‌kg, for elastic collision e=1.
m1

u1=u

───▶──

M

u2=0

Suppose initially body m1 moves with velocity v after collision velocity becomes (‌

u

10

).
Let after collision velocity of M block becomes (v2)
By conservation of momentum
m1u1+m2u2=m1v1+m2v2
or ‌‌5u+M×0=5×‌

u

10

+Mv2 or
5u=‌

u

2

+Mv2 . . . (i)
Since, ‌‌v1−v2=−e(u1−u2)
‌

u

10

−v2=−1(u)
or ‌

u

10

+u=v2
‌

11u

10

=v2 . . . (ii)
Substituting value of v2 in Eq. (i) from Eq. (ii), we get
or 5u‌=‌

u

2

+M(‌

11u

10

)
5−‌

1

2

‌=M(‌

11

10

)
M‌=‌

9×10

2×11

M‌=‌

45

11

‌=4.09‌kg