Question

A particle of mass m strikes another particle of
same mass at rest elastically. After collision if
velocity of one of the particle is 3i^ – 2j^ m/s, then
the other must have a velocity equals to
(1) i^+j^
(2) 2i^ +3j^
(3) 2i^-j^
(4) i^+3j^​

Answer 1

answer : (-3i + 2j ) m/s [ options are incorrect ]

explanation : a/c to question, A particle of mass m strikes another particle of same mass at rest elastically.

it means, initial linear momentum of system of these particle = 0

after striking , velocity of one of them is (3i - 2j) m/s then we have to find velocity of another.

using law of conservation of linear momentum.

so, $P_i=P_f$

or, $0=m_1v_1+m_2v_2$

here, $m_1=m_2=m$

so, $v_1=-v_2$

it means, velocity of another particle is same in magnitude but opposite in direction

so, velocity of another particle is -(3i - 2j) =( - 3i + 2j) m/s

Answer 2

Explanation:

The options are given wrong

the answer is _3i^ +2j^

magnitude is same but directions will be reversed