Question

A spring is held compressed. its stored energy is 2.4 joule its end are in contact with mass of 1 gm and 48 gm placed on a smooth horizontal surface. when the spring is released ,the mass of 48 gm will acquire a velocity of-

• A. $\frac{2.40}{149}m/s$
• B. $24.5m/s$
• C. $\frac{10}{7}m/s$
• D. $\frac{{10}^4}{7}m/s$

Answer 1

The correct option is C $\frac{10}{7}m/s$

$\frac{1}{2}{m}_1{v}_1^2+\frac{1}{2}{m}_2{v}_2^2=2.4$

or, $m_1{v}_1^2+m_2{v}_2^2=4.8$

Now, $m_1{v}_1=m_2{v}_2$

or, $v_1=48v_2$

Using equation $\left(i\right)$ $\frac{1}{1000}{\left(48v_2\right)}^2+\frac{48}{1000}{v}_2^2=4.8$

or, $\frac{48}{1000}\left({49v}_2^2\right)=4.8$

$v_2=\frac{10}{7}m/s$.