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 m/s and 2 kg second part moving with a velocity of 8 m/s . If the third part flies off with a velocity of 4 m/s , its mass would be:

5 kg

Mv Cos \(\theta\) = 12

Mv Sin \(\theta\) = 16

Tan \(\theta = \frac{4}{3} \)

M = \(\frac{12 × 5}{4 × 3}\) = \(\frac{60}{12}\)

M = 5 kg