A soldier carrying a gun with parachute A soldier with a machine gun, falling from an airplane gets detached from his parachute. He is able to resist the downward acceleration if he shoots 40 bullets a second at the speed of 500m/s. If the weight of a bullet is 49gm, what is the weight of the man with the gun? Ignore resistance due to air and assume the acceleration due to gravity g=9.8m/s2
Solution:
Let M be the mass of the soldier and Mg be the mass of the gun. 
To nullify the downward acceleration, 40 bullets are shot at the speed of 500m/s.
The force equation can be written as:
$$(M+M_g)9.8=40\times500\times49\times10^-3$$
$$\Rightarrow (M+M_g)=100Kg$$
Therefore,
the weight of the man with the gun=100Kg.