Question

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 $12m{s}^{-1}$ and $2kg$ second part moving with a velocity of $8m{s}^{-1}$. If the thirds part files off with a velocity of $4m{s}^{-1}$, its mass would be:

• A. $3kg$
• B. $5kg$
• C. $7kg$
• D. $17kg$

Answer 1

The correct option is B $5kg$

An explosion blows a rock into three parts Two parts go off at right angles to each other. These two are, $1kg$ first part moving with a velocity of $12m/s$ and $2kg$ second part moving with a velocity of $8m/s$. If the thirds part files off with a velocity of $4m/s$its mass would be

${\overrightarrow{P}}_1+{\overrightarrow{P}}_2+{\overrightarrow{P}}_3=0$

$\overrightarrow{|P_3|}=\overrightarrow{|P_1}+\overrightarrow{P_2|}$

$m\times 4=\sqrt{P_1^2+P_2^2}=\sqrt{{12}^2+{16}^2}=20$

$m\ast 4=20kg$

$m=5kg$