Question

A boy of mass $60kg$ is standing over a platform of mass $40kg$ placed over a smooth horizontal surface. He throws a stone of mass $1kg$ wth velocity $u=10m/s$ at an angle of ${45}^o$ with respect to ground. The displacement of platform (With boy) on the horizontal surface when the stone lands on the ground is ($g=10m/s^2$).

• A. $25cm$
• B. $5cm$
• C. $10cm$
• D. $50cm$

Answer 1

The correct option is C $10cm$

$T=\frac{2\times 10}{10}\times \frac{1}{\sqrt{2}}=\sqrt{2}sec$
$x=v_{\left(x\right)}t=\left(\frac{mu\cos \theta }{m_1+m_2}\right)t=\frac{\left(\frac{1\times 10}{\sqrt{2}}\right)\sqrt{2}}{100}=10cm$