An explosion blows a rock into three parts Two parts go off at right angles to each other. These two are, 1 ~kg first part moving with a velocity of 12 ~ms^ -1 and 2 ~kg second part moving with a velocity of 8 ~ms^ -1 .

Correct answer: B. 5 ~kg aligned P _1+ P _2+ P _3 & =0 | P _3| & =| P _1+ P _2| m ×4 & = P_1^2+P_2^2 & = 12^2+16^2 ~m& =5 ~kg aligned

NEET 2009

NEET 2009 · Physics · Center of Mass, Momentum and Collision

An explosion blows a rock into three parts Two parts go off at...

An explosion blows a rock into three parts Two parts go off at right angles to each other. These two are,

1 \mathrm{~kg}

first part moving with a velocity of

12 \mathrm{~ms}^{-1}

and

2 \mathrm{~kg}

second part moving with a velocity of

8 \mathrm{~ms}^{-1}

. If the thirds part files off with a velocity of

4 \mathrm{~ms}^{-1}

, its mass would be :

B. $5 \mathrm{~kg}$

\begin{aligned}\overrightarrow{\mathrm{P}}_1+\overrightarrow{\mathrm{P}}_2+\overrightarrow{\mathrm{P}}_3 & =0 \\ \left|\overrightarrow{\mathrm{P}}_3\right| & =\left|\overrightarrow{\mathrm{P}}_1+\overrightarrow{\mathrm{P}}_2\right| \\ \mathrm{m} \times4 & =\sqrt{\mathrm{P}_1^2+\mathrm{P}_2^2}\\ & =\sqrt{12^2+16^2}\\ \mathrm{~m}& =5 \mathrm{~kg} \end{aligned}