Try this solution (if it is possible, check it in other sources):
1. for m_Tarzan=75kg., initial_height=4m., end_height=0 m. and g=10 N/kg. Energy is:
[tex]E=m_{Tarzan}*(H_{initial}-H_{end})*g=75*4*10=3000(J).[/tex]
2. The same value of Energy is applied for m_Tarzan+Jane=75+50=125 kg.:
[tex]E=\frac{m_{Tarzan+Jane}* Speed^2}{2}; \ => \ Speed=\sqrt{ \frac{2*E}{m_{Tarzan+Jane}}};[/tex]
3. According to the formula of the Speed:
Speed=sqrt(6000/125)=sqrt(48)=4sqrt(3)≈4*1.71=6.84 (m/s)
Answer: 6.84 (m. per sec.)
