Question

Erica (39kg \;kg ) and Danny (45kg \;kg ) are bouncing on a trampoline. Just as Erica reaches the high point of her bounce, Danny is moving upward past her at 4.8m/s \; m/s . At that instant he grabs hold of her.

What is their speed just after he grabs her?

Answer 1

2.57142857143 m/s

Step-by-step explanation:

`m_1` = Mass of Danny = 45 kg

`m_2` = Mass of Erica = 39 kg

`u_1` = Velocity of Danny = 4.8 m/s

v = Combined velocity

In this system the linear momentum is conserved

`m_1u_1=(m_1+m_2)v\\\Rightarrow v=(m_1u_1)/(m_1+m_2)\\\Rightarrow v=(45* 4.8)/(39+45)\\\Rightarrow v=2.57142857143\ m/s`

The speed of Erica and Danny is 2.57142857143 m/s