To solve this exercise it is necessary to take into account the concepts related to Tensile Strength and Shear Strenght.
In Materials Mechanics, generally the bodies under certain loads are subject to both Tensile and shear strenghts.
By definition we know that the tensile strength is defined as

Where,
Tensile strength
F = Tensile Force
A = Cross-sectional Area
In the other hand we have that the shear strength is defined as

where,
Shear strength
Shear Force
Parallel Area
PART A) Replacing with our values in the equation of tensile strenght, then

Resolving for F,

PART B) We need here to apply the shear strength equation, then



In such a way that the material is more resistant to tensile strength than shear force.
I would say its c . <span>National Academy of Forensic Science</span>
As we know that friction force on box is given by

here we know that

here we have
m = 12 kg

so now we have

now we will have


so it required minimum 49 N(approx) force to move the block
Answer:
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Explanation:
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This question involves the use of the equations of motion for vertical motion.
The time taken by the stones P and Q to reach the ground is the same, that is "2 s".
The velocity with which Q hits the ground is "20 m/s".
The time taken by the stones to reach the ground can be calculated by using the second equation of motion for the vertical motion:

For both the stones P and Q:
h = height = 20 m
= initial velocity = 0 m/s
t = time = ?
g = acceleration due to gravity = 10 m/s²
Therefore,

<u>t = 2 s</u>
<u></u>
Hence, the time taken by both the stones to reach the ground <u>is the same</u>.
To find the final velocity of stone Q we will use the first equation of motion for the vertical motion:

Learn more about equations of motion here:
brainly.com/question/20594939?referrer=searchResults
The attached picture shows the equations of motion in the horizontal and vertical directions.