Question

A ball of mass 0.5kg looses one third of its velocity when it makes a head on collision with an identical ball 'q' at rest after the collision 'q' cloves off with a speed of 20m per seconds in the original direction of 'p' of d first ball calculate the initial velocity of p

Answer 1

We can use conversation of linear momentum:

(1) $m_p \cdot V_1 = m_p \cdot V_1 \cdot \frac{1}{3} + m_q \cdot V_2$ ,

where $m_p = m_q = 0.5kg = \frac{1}{2} kg - mass$ of the first ball;

$V_{2} = 20\frac{m}{s}$ , speed of the second ball "q" after collision.

$V_{1}$ - speed of the first ball p

$m_p \cdot V_1 - \frac{m_p}{3} \cdot V_1 = V_2 \cdot m_q$

Let's put values $V_{2}$ and $m_{q}$ , $m_{p}$ into equation. We will have:

$0.5\cdot V_{1} - 0.16\cdot V_{1} = 10$

$0.34\cdot V_{1} = 10$

ANSWER: $V_{1} = 29.4 \, \text{m/s}$