Question

Two bodies of masses 2 kg and 4 kg are moving
with velocities 2 m/s and 10m/s respectively along
same direction. Then the velocity of their centre of
mass will be
(A) 8.1 m/s
(B) 7.3 m/s
(C) 6.4 m/s
(D) 5.3 m/s​

Answer 1

Answer:

(B)

Explanation:

M1 = 2 m/s

M2 = 4 m/s

V1 = 2 m/s

V2 = 10 m/s

Cm = M1V1 + M2V2

M1 + M2

= 2(2) + 4(10)

2+4

= 4 + 40

6

= 44

6

= 7.3 m/s

Answer 2

$\huge{\bold{\underline{\underline{....Answer....}}}}$

$\huge{\bold{\underline{Given:-}}}$

$\large{m_1 = 2 \: Kg}$

$\large{m_2 = 4 \: Kg}$

$\large{v_1 = 2 \: m/s}$

$\large{v_2 = 10 \: m/s}$

$\huge{\bold{\underline{Explanation:-}}}$

As we know,

The centre of mass velocity can be find out through

$\large{\bold{V_{COM} = \frac{M_1V_1 + M_2V_2}{M_1 + M_2}}}$

Substituting the values.

$\large{ \implies V_{COM} = \frac{2 \times 2 + 4 \times 10}{2 + 4}}$

$\large{ \implies V_{COM} = \frac{4 + 40}{6}}$

$\large{ \implies V_{COM} = \frac{44}{6}}$

$\large{ \implies V_{COM} = \frac{ \cancel{44}}{ \cancel{6}}}$

$\large{ \implies V_{COM} = \frac{22}{3}}$

$\huge{\boxed{\boxed{V_{COM} = 7.3 \: m/s}}}$

So, the velocity of centre of mass is 7.3 m/s.