A tennis ball of mass m strikes a wall with a velocity v and retraces the same path. Calculate the change in momentum

Question

A tennis ball of mass m strikes a wall with a velocity v and retraces the same path. Calculate the change in momentum (A) +4mv (B) - 4mv (C) +2 mv (D) -2 mv

Tardigrade Admin · Accepted Answer

Initial momentum, pi = mv Final momentum, pf= -mv ∴ Change in momentum = pf - pi = -mv - mv = -2mv Initial momentum, pi = - mv Final momentum, pf= mv ∴ Change in momentum = pf - pi = mv -(- mv) = + 2mv

Q. A tennis ball of mass $m$ strikes a wall with a velocity $v$ and retraces the same path. Calculate the change in momentum

$+ 4 m v$

$- 4 m v$

$+ 2 m v$

$- 2 m v$

Initial momentum, $p_{i} = m v$
Final momentum, $p_{f} = - m v$
$∴$ Change in momentum $= p_{f} - p_{i}$
$= - m v - m v = - 2 m v$
Initial momentum, $p_{i} = - m v$
Final momentum, $p_{f} = m v$
$∴$ Change in momentum $= p_{f} - p_{i}$
$= m v - (- m v) = + 2 m v$

Q. A tennis ball of mass m strikes a wall with a velocity v and retraces the same path. Calculate the change in momentum

+4mv

−4mv

+2mv

−2mv