D is the best answer. In many physics problems we treat an extended object as if it were a point with the same mass located at the center of mass.
A) The resultant force is 30.4 N at 
B) The resultant force is 18.7 N at 
Explanation:
A)
In order to find the resultant of the two forces, we must resolve each force along the x- and y- direction, and then add the components along each direction to find the components of the resultant.
The two forces are:
at
above x-axis
at
above y-axis
Resolving each force:


So, the components of the resultant are:

And the magnitude of the resultant is:

And the direction is:

B)
In this case, the 15 N is applied in the opposite direction to the 20 N force. Therefore we need to re-calculate its components, keeping in mind that the angle of the 15 N force this time is

So we have:

So, the components of the resultant this time are:

And the magnitude is:

And the direction is:

Learn more about vector addition:
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In the experiment of free fall bob released a bag of mass 1 lb
so here we can say that initial speed of the bag is Zero
time taken by the bag to free fall is given as
t = 1.5 s
also the acceleration of free fall is given as
a = 9.8 m/s^2
now we will use kinematics equation here for finding the distance of free fall




so the bag will fall down by total distance of 11.025 m from its initial released position.
Energy slowly leaks outward through the radiative diffusion of photons that repeatedly bounce off ions and electrons.
<h3>What is radiative diffusion?</h3>
A radiation zone is a layer of a star's core where energy is mostly carried toward the outside by radiative diffusion and thermal conduction rather than convection.
As photons, energy passes through the radiation zone as electromagnetic radiation.
The radiative diffusion of photons that repeatedly bounce off ions and electrons progressively drains energy outward.
Hence,radiative diffusion is correct answer.
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