Two putty balls of equal mass moving with equal velocity in mutua… - Vidyadip

MCQ

Two putty balls of equal mass moving with equal velocity in mutually perpendicular directions, stick together after collision. If the balls were initially moving with a velocity of $45\sqrt 2 \,m{s^{ - 1}}$ each, the velocity of their combined mass after collision is .................. $\mathrm{m} / \mathrm{s}^{-1}$

A
$45\sqrt 2$
✓
$45$
C
$90$
D
$22.5\sqrt 2$

✓

Answer

Correct option: B.

$45$

b
(b)Initial momentum
$\vec P = m45\sqrt 2 \;\hat i + m45\sqrt 2 \;\hat j$ $⇒$ $|\vec P| = m \times 90$
Final momentum $2m \times V$
By conservation of momentum $2m \times V = m \times 90$
$V = 45\,m/s$

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