Question

Conservation of momentum

Answer 1

Answer: 6.21 m/s opposite to Janet

Explanation:

Given

mass of Janet $m_j=59\ kg$

mass of Sarah $m_s=32\ kg$

The initial velocity of Janet $u_1=7\ m/s$

The final velocity of Janet after the collision is $v_1=2\ m/s$

the final velocity of Sarah after the collision is $v_2=3\ m/s$

Conserving linear momentum

$\Rightarrow m_ju_1+m_su_2=m_jv_1+m_sv_2\\\Rightarrow 59\times 7+32\times u_2=59\times 2+32\times 3\\\Rightarrow 32u_2=118+96-413\\\Rightarrow u_2=\frac{-199}{32}=-6.21\ m/s$

Negative indicates the direction of velocity is opposite than of Janet