8. A karate master strikes a board with an initial velocity of 10 m/s, decreasing to 1 m/s as his hand passes through the board. If the time of contact with the board is 0.002 s, and the mass of the coordinated hand and arm is 1 kg, what is the force exerted on the board. a. 1000 N b. 1800 N c. 2700 N d. 4500 N - well, I lost my book cuz my backpack got stolen and I have an older physics book i got from a freind and the pages dont match up with my study guide. I cant find the right equation for this. I need an equation that uses change in velocity, contact time, and mass of the object to get F in Newtons. If anyone can show me how I do this or at least point me in the right direction I would appreciate it.