Answer:
buoyant force on the block due to the water= 10 N
Explanation:
We know that
buoyant force(F_B) on a block= weight of the block in air (actual weight) - weight of block in water.
Given:
A block of metal weighs 40 N in air and 30 N in water.
F_B = 40-30= 10 N
therefore, buoyant force on the block due to the water= 10 N
To solve this problem it is necessary to apply the concewptos related to Torque, kinetic movement and Newton's second Law.
By definition Newton's second law is described as
F= ma
Where,
m= mass
a = Acceleration
Part A) According to the information (and as can be seen in the attached graph) a sum of forces is carried out in mass B, it is obtained that,


In the case of mass A,


Making summation of Torques in the Pulley we have to



Replacing the values previously found,





Replacing with our values


PART B) Ignoring the moment of inertia the acceleration would be given by



Therefore the error would be,



Assuming the objects roll down the inclined plane, yes.
If the object never touches the plane, then no.
Yes, they live off of other organisms and harm the organisms.