Question

A projectile has a momentum of 1.6 x 104 kg-m/s and a velocity of 200 m/s. What is its mass and its weight?

Answer 1

Explanations & Calculations

• The momentum of a particle is given by $\small \vec{P}=m\vec{v}$, then the mass of the projectile can be calculated to be

$\qquad\qquad \begin{aligned} \small m&=\small \frac{1.6\times 10^4\,kgms^{-1}}{200\,ms^{-1}}\\ &=\small \bold{80\,kg} \end{aligned}$

• Since the momentum is a vector quantity, the direction it has is along the same direction of its velocity. (resultant velocity of its vertical & horizontal components)

• Finally, the weight of the projectile is

$\qquad\qquad \begin{aligned} \small W&= \small mg\\ &=\small 80\,kg\times 9.8\,ms^{-2}\\ &= \small \bold{784\,N} \end{aligned}$