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Essentially, a control variable is what is kept the same throughout the experiment, and it is not of primary concern in the experimental outcome. Any change in a control variable in an experiment would invalidate the correlation of dependent variables (DV) to the independent variable (IV), thus skewing the results.
This question involves the concepts of Wein's displacement law and characteristic wavelength.
The blackbody temperature will be "3.22 x 10⁵ k".
<h3>WEIN'S DISPLACEMENT LAW</h3>
According to Wein's displacement law,

where,
= characteristic wavelength = 9 μm = 9 x 10⁻⁹ m- T = temperature = ?
- c = Wein's displacment constant = 2.897 x 10⁻³ m.k
Therefore,

T = 3.22 x 10⁵ k
Learn more about characteristic wavelength here:
brainly.com/question/14650107
Yes. Kinetic energy is a form of mechanical energy and friction will turn that kinetic energy into heat.
The force applied to the cannonball and cannon is equal. The explosion inside the cannon will generate a pressure which will turn into a force on both cannonball and cannon. The cannon being heavier and fixed to the ground will move a bit, but the cannonball will be thrown away, fired.