Question

Tarzan (75 kg) swings from 4 metres high on a vine down to ground level and catches Jane (50 kg). How fast are they moving after he cares her?

Answer 1

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:

$E=m_{Tarzan}*(H_{initial}-H_{end})*g=75*4*10=3000(J).$

2. The same value of Energy is applied for m_Tarzan+Jane=75+50=125 kg.:

$E=\frac{m_{Tarzan+Jane}* Speed^2}{2}; \ => \ Speed=\sqrt{ \frac{2*E}{m_{Tarzan+Jane}}};$

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.)