With what magnitude of force does a ball of mass 0.75 kilograms need to be hit so that it accelerates at the rate of 25 meters/ second 2 ? assume that the ball undergoes motion along a straight line.
a. 10 newtons
b. 19 newtons
c. 33.3 newtons
d. 40 newtons

Do you remember seeing Newton's 2nd Law ?

                                   F = m A

                               Force = (mass) x (acceleration)

The question tells you the mass and the acceleration. 
All YOU have to do is take the numbers and pluggum
into Newton's 2nd law.

                               F  =  m  A

                                   =  (0.75 kg) (25 m/s²)

                                   =  (0.75 x 25)  kg-m/s²

                                   =       18.75 Newtons  .   

Notice that this is the ball's acceleration only as long as the force is
acting on it.  If it's a hit, then as soon as the ball leaves the bat, it stops accelerating ... it just sails away at whatever speed it had when the bat
stopped pushing it.

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