A0.45 kg soccer ball changes its velocity by 20.0 m/s due to a force applied to it in 0.10 seconds. what force was necessary for this change in velocity?

For this problem, we will need the famous equation F=ma, as detailed by Isaac Newton.

F=mass x acceleration, where Force is in Newtons.

20 m/s represents the quantity of speed change, but to use in the equation, we need acceleration, not speed. Acceleration is the velocity change over a unit time, so changing 20 m/s in 0.1 seconds means that the acceleration was 200 m/s^2.

Plugging in all your numbers, you find:

F=(0.45 kg)(200 m/s^2) = 90 N of force.