Answer:
The recoil speed of the man and rifle is .
Explanation:
The expression for the force in terms of mg is as follows;
F=mg
Here, m is the mass and acceleration due to gravity.
Rearrange the expression for mass.
Calculate the combined mass of the man and rifle.
Put .
The expression for the conservation of momentum is as follows as;
Here, is the mass of the man and rifle,
is the mass of the rifle,
are the initial velocities of the man and bullet and
are the final velocities of the man and rifle and rifle.
It is given in the problem that a rifle with a weight of 25 N fires a 4.5-g bullet with a speed of 240 m/s.
Convert mass of rifle from gram to kilogram.
Put ,
,
,
and
.
Therefore, the recoil speed of the man and rifle is .