Question

A 40 kg girl skates at 3.5 m/s on the ice toward her 65 kg friend who is standing still,with open arms. As they collide and hold each other, what is the speed of the couple?Also, after you get an answer. ROUND NUMBERS TO 2 DECIMAL PLACES.

Answer 1

We will have the following:

We solve using the conservation of momentum:

$\begin{gathered} (40kg)(3.5m/s)+(65kg)(0m/s)=(40kg+65kg)v\Rightarrow140kg\ast m/s=(105kg)v \\ \\ \Rightarrow v=\frac{140kg\ast m/s}{105kg}\Rightarrow v=\frac{4}{3}m/s \\ \\ \Rightarrow v\approx1.33m/s \end{gathered}$

So, the final speed of the couple is approximately 1.33 m/s.