Mass does not affect the pendulum's swing. The longer the length of string, the farther the pendulum falls; and therefore, the longer the period, or back and forth swing of the pendulum. The greater the amplitude, or angle, the farther the pendulum falls; and therefore, the longer the period.
Answer:
If the rifle is held loosely away from the shoulder, the recoil velocity will be of -8.5 m/s, and the kinetic energy the rifle gains will be 81.28 J.
Explanation:
By momentum conservation, <em>and given the bullit and the recoil are in a straight line</em>, the momentum analysis will be <em>unidimentional</em>. As the initial momentum is equal to zero (the masses are at rest), we have that the final momentum equals zero, so

now we clear
and use the given data to get that

<em>But we have to keep in mind that the bullit accelerate from rest to a speed of 425 m/s</em>, then <u>if the rifle were against the shoulder, the recoil velocity would be a fraction of the result obtained</u>, but, as the gun is a few centimeters away from the shoulder, it is assumed that the bullit get to its final velocity, so the kick of the gun, gets to its final velocity
too.
Finally, using
we calculate the kinetic energy as

Given that the mass is m = 0.2 kg and the displacement is x = 3 cm = 0.03 m
We have to find the spring constant and potential energy.
The spring constant can be calculated by the formula

Here, k is the spring constant.
g = 9.8 m/s^2 is the acceleration due to gravity.
Substituting the values, the spring constant will be

The potential energy can be calculated as
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