Question

In a head on elastic collision of a heavy vehicle moving with a velocity of $10{\text{ms}}^{-1}$ and a small stone at rest, the stone will fly away with a velocity equal to

• A. $5{\text{ms}}^{-1}$
• B. $10{\text{ms}}^{-1}$
• C. $20{\text{ms}}^{-1}$
• D. $40{\text{ms}}^{-1}$

Answer 1

The correct option is C $20{\text{ms}}^{-1}$

For elastic collision,
If $m_1>>m_2,$ then $v_1\approx u_1$ and $v_2=2u_1-u_2$
$v_2=2u_1-0=2\times 10=20\text{m/s}$
$\therefore \left(c\right)$