Let us see. We have that Newton's Law holds in this case, so 
where a is the acceleration of the ball, F the forces acting on it and m its mass. There are 2 forces acting on it, the force of gravity W and air resistance R. We can easily see that these two act in opposite directions (gravity towards the ground, resistance upwards), so |ΣF|=W-R (1) . We have that W=m*g where <span>g=9.81 m/s2. We also have that ΣF=9.40*m. From this relationship, substituting into (1) all the known values, we get that R=m(9.81*-9.40)=m*0,41. We take then the ratio R/W. This is equal to:
. This is our final answer.
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