A 10 kg ball moving with velocity 2 ms-1 collides with a 20 kg mass initially at rest. If both of them coalesce, the final velocity of combined mass is

Question

A 10 kg ball moving with velocity 2 ms-1 collides with a 20 kg mass initially at rest. If both of them coalesce, the final velocity of combined mass is (A) (3/4) ms-1 (B) (1/3) ms-1 (C) (3/2) ms-1 (D) (2/3) ms-1

Tardigrade Admin · Accepted Answer

Using law of conservation of momentum m1u1+m2u2=(m1+m2)v Here ,m1=10 kg ,m2 =20 kg ,u1=2 ms-1,u=0 = 10 × 2 +0= (10+20)v or v=(20/30)=(2/3)ms-1

Q. A 10 kg ball moving with velocity $2 m s^{- 1}$ collides with a 20 kg mass initially at rest. If both of them coalesce, the final velocity of combined mass is

$\frac{3}{4} m s^{- 1}$

$\frac{1}{3} m s^{- 1}$

$\frac{3}{2} m s^{- 1}$

$\frac{2}{3} m s^{- 1}$

Using law of conservation of momentum
$m_{1} u_{1} + m_{2} u_{2} = (m_{1} + m_{2}) v$
Here , $m_{1} = 10 k g, m_{2} = 20 k g, u_{1} = 2 m s^{- 1}, u = 0$
= 10 $\times 2 + 0 = (10 + 20) v$
or $v = \frac{20}{30} = \frac{2}{3} m s^{- 1}$

Q. A 10 kg ball moving with velocity 2ms−1 collides with a 20 kg mass initially at rest. If both of them coalesce, the final velocity of combined mass is

43​ms−1

31​ms−1

23​ms−1

32​ms−1