Phy numarical 9.7

Dear Student,
Given :
m_g = 40 kg

u_g = 5 m/s

m_c= 3 kg

u_c = 0
Applying conservation of linear momentum, 

P_i = P_f

or,
=> m_gu_g + m_cu_c= m_gv_g + m_c v_c

=> 40 × 5 + 3 X 0 = (m_g + m_c) × v (since, after the girl jump on cart, they both move with same velocity)

=> 200 = (40 + 3)v
=> v = 200/43
=> v = 4.65 m/s 

Regards