All of the above .........
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:

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It’s doesn’t change meaning it’s 0
Answer:
The centripetal acceleration of the runner is
.
Explanation:
Given that,
A runner completes the 200 m dash in 24.0 s and runs at constant speed throughout the race. We need to find the centripetal acceleration as he runs the curved portion of the track. We know that the centripetal acceleration is given by :

v is the velocity of runner

Centripetal acceleration,

So, the centripetal acceleration of the runner is
. Hence, this is the required solution.