Answer:
A: The acceleration is 7.7 m/s up the inclined plane.
B: It will take the block 0.36 seconds to move 0.5 meters up along the inclined plane
Explanation:
Let us work with variables and set

As shown in the attached free body diagram, we choose our coordinates such that the x-axis is parallel to the inclined plane and the y-axis is perpendicular. We do this because it greatly simplifies our calculations.
Part A:
From the free body diagram we see that the total force along the x-axis is:

Now the force of friction is
where
is the normal force and from the diagram it is 
Thus
Therefore,

Substituting the value for
we get:

Now acceleration is simply

The negative sign indicates that the acceleration is directed up the incline.
Part B:

Which can be rearranged to solve for t:

Substitute the value of
and
and we get:
which is our answer.
Notice that in using the formula to calculate time we used the positive value of
, because for this formula absolute value is needed.
Answer:
Aristotle was blind, therefore could not see change in positions. Aristotle could see no detectable change in the positions of the stars, thought Earth was immovable.
Explanation:
The electrostatic force between two charges is given by

where
k is the Coulomb's constant
q1 and q2 are the two charges
r is their separation
In this problem, the two charges are identical, so we can call them q1=q2=q, and the formula becomes

Since we know the magnitude of the force and the separation between the two charges, we can re-arrange the equation to find the value of each charge:
Primary clarifiers removing biological nutrients is not true. Primary clarifiers
involves the use of processes such as sedimentation in order to remove
particles floating or other inorganic solids from the waste water.
Biological nutrients such as nitrogen and phosphorus are found in waste
water and removal of these important nutrients for other uses is a part of
waste water management.
The secondary clarifiers are the ones responsible for the removal of
biological nutrients in the waste water through biofiltration etc.
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