Answer:
P=6.25N and Q=16.25N
Explanation:
In order to solve this problem we must first draw a free body diagram for both situation, (see attached picture).
Now, we need to analyze the two free body diagrams. So let's analyze the first diagram. Since the body is accelerated, then the sum of forces is equal to mass times acceleration, so we get:
We can assume there will be only the two mentioned forces P and Q, so
the sum of forces will be:
P+Q=ma
P+Q=22.5N
We can do the same analysis for the second free body diagram:
Q-P=10.5N
so now we have a system of equations we can solve by elimination:
Q+P=22.5N
Q-P=10.5N
Now, we can add the two equations together so the P force is eliminated, so we get:
2Q=32.5N
now we can solve for Q:
so
Q=16.25N
Now we can use any of the equations to find P.
Q+P=22.5N
P=22.5N-Q
when substituting for Q we get:
P=22.5N-16.25N
so
P=6.25N
