Answer:

Explanation:
Given that
Mass of rifle = M
Initial velocity ,u= 0
Mass of bullet = m
velocity of bullet = v
Lets take final speed of the rifle is V
There is no any external force ,that is why linear momentum of the system will be conserve.
Initial linear momentum = Final linear momentum
M x 0 + m x 0 = M x V + m v
0 = M x V + m v

Negative sign indicates that ,the recoil velocity will be opposite to the direction of bullet velocity.
The gravitational force between two object depends on their masses and on their distance.
Since the formula is

If the masses grow, the force also grows. But I'm assuming the two objects are fixed, so you can't enlarge their mass.
So, the only option remaining is to lower their distance: since it sits at the denominator, a smaller value of d results in a bigger value for F.
So, if you reduce the distance between two objects, the gravitational force between them will always result in an increase
Answer:
x = 0.0537 m or 5.37 cm
Explanation:
Given:
spring constant'k'= 4900 N/m
radius 'r' =0.029 m
Area 'A' =r²π = 0.029²π => 2.6 x
m²
Here, Pressure 'P' is given by,
Pressure = Force / Area
And we know that, for a spring :
F = kx, where k is the spring constant and x is the change in length.
P = kx/A
As P = 101325 Pa
101325 = 4900x / ( 2.6 x
)
x = 0.0537 m or 5.37 cm