Answer to Question #208998 in Mechanics | Relativity for Barbara

Question

 calculate a dog running at a speed of 32 km/ hr jumps into stationary canoe on the river in to a stationary canoe the mass of the dog is 14kg the canoe and roller is 160 kg lets assume the water force is frictionless wgat is the speed of the canoe after collision

Answer 1

Explanations & Caculations

• Since the canoe is resting on the water which is considered almost smooth, the dog-canoe system could be thought of as a system experiencing no external forces thus in which linear momentum is conserved.
• Then it's about applying the concept of conservation of linear momentum for the dog-canoe system.
• Assume the dog reaches the canoe after jumping onto it at the same speed which it was moving before jumping.
• After both the dog and the canoe travel at the same speed $\small (V_{d,c})$ . (dog would be on the canoe)
• Then,

$\qquad\qquad \begin{aligned} \small \overrightarrow{m_d.v_d}+\overrightarrow{m_c.v_c}&=\small \overrightarrow{(m_d+m_c).V_{d,c}}\\ \small V_{d,c}&=\small \frac{m_d.v_d+m_c.0}{(m_d+m_c)}\\ &=\small \frac{14kg\times32kmh^{-1}}{(14kg+160kg)}\\ &=\small \bold{2.57\,kmh^{-1}} \end{aligned}$