Question

Two rugby players run towards each other and have an inelastic collision. Given the mass 70 kg and 60 kg respectively, and velocity 3 ms-1 and 4 ms-1. Calculate the final velocity and its direction of the respective players. Discuss how a rugby player’s bone develops if continuously performing the weight bearing exercise using Wolff’s Law and bone remodeling theory.  

Answer 1

Explanations & Calculations

• Apply conservation of linear momentum to the situation described.
• Let's think the 70kg player was moving to right and the other, to left.

$\qquad\qquad \begin{aligned} \small \to m_1v_1+m_2v_2 &=\small (m_1+m_2)V\\ \small V&=\small \frac{(70\times3)-(60\times4)}{70+60}\\ &=\small -0.39\,ms^{-1} \end{aligned}$

• The minus mark here is due to the velocity being in the other way around, to the left.
• Both of them move slightly to right.