Question

a model rocket is launched at an angle of 55 to the horizontal with a momentum of 20 kg-m/. If the vertical component of its velocity is 40 m/s what is the mass of the rocket?

Answer 1

$Given:\\ \alpha =55^\circ\\p=20kg\cdot \frac{m}{s} \\v_v=40 \frac{m}{s} \\\\Find:\\m=?\\\\Solution:\\\\p_v=mv_v\Rightarrow m= \frac{p_v}{v_v} \\\\ \frac{p_v}{p} =\cos \alpha \Rightarrow p_v=p\cos \alpha \\\\m= \frac{p\cos \alpha }{v_v} \\\\m= \frac{20kg\cdot \frac{m}{s} \cdot \cos 55^\circ }{40 \frac{m}{s} } \approx 0.287kg=287g$