Answer:
3.8 kg
Explanation:
The torque, <em>τ</em>, due to the force, <em>F</em>, is given by

where <em>r</em> is the radius.
This torque is also given by

where <em>I</em> and <em>α</em> are respectively the moment of inertia and the angular acceleration.
For a solid disk, its moment of inertia for an axis though its centre and perpendicular to its face is given by

where <em>m</em> is its mass and <em>r</em> is its radius.
Hence, we have


Answer:
C. 0.2 Hertz
Explanation:
The frequency of a spring is equal to the reciprocal of the period:

where
f is the frequency
T is the period
For the spring in this problem,
T = 5 s
therefore, the frequency is

B because 2800 divide by 40 is 20
C
because 40 j dived by 5 seconds is 8 work