Question 125: Centre of Mass and Rotational Motion

Question

An object of mass m
1
collides with another object of mass m
2
, which is at rest. After the collision the objects move with equal speeds in opposite direction. The ratio of the masses m
2
: m
1
is :

Accepted Answer

Before collision
After collision,
Applying momentum conservation,
m
1
v
1
= m
2
v $$-$$ m
1
v ..... (1)
As collision is elastic,
$$ 	herefore $$ e = 1
$$ \Rightarrow $$ $${{v - ( - v)} \over {0 - {v_1}}} = 1$$
$$ \Rightarrow $$ v
1
= 2v ..... (2)
Put value of v
1
in equation (1),
m
1
(2v) = (m
2
$$-$$ m
1
)v
$$ \Rightarrow $$ 2m
1
= m
2
$$-$$ m
1
$$ \Rightarrow $$ 3m
1
= m
2
$$ \Rightarrow $$ $${{{m_2}} \over {{m_1}}} = {3 \over 1}$$

Answer

1 : 1

Answer

3 : 1

Answer

2 : 1

Answer

1 : 2

Centre of Mass and Rotational Motion

An object of mass m 1 collides with another object of mass m 2 , which is at rest. After the collision the objects move with equal speeds in opposite direction. The ratio of the masses m 2 : m 1 is :

Choose the correct answer: