1. So first off, this isn't a homework problem but I figured this would be the best place to post this kind of question. I have an air powered cannon that can shoot potatoes. It is basically a beefed up version of those little potato guns you can buy at FredMyers. You pump up a chamber with air so it is compressed, and then manually turn a valve that releases the pressure through the barrel, firing whatever is inside of the barrel. So I need to find out how fast the muzzle velocity of the potato is, and how much force it is exerting on a target from the distance of point blank (about a foot long.) I don't have a chronograph so I need to use the method of the ballistic pendulum, which I believe boils down V=[(mb+mp)*√(2*g*h)] /mb for the velocity, but I have no Idea how to find the force of the bullet upon impact. 2. What I know is that my projectile is about 0.17kg in weight (I say about because I have an old scale and haven't gotten a more precise scale yet so I'm just rounding the best I can.)(mb) My pendulum will be 4 pounds which is about 1.8kg.(mp) And since I haven't actually tested this, for sake of example, I'll say the pendulum moves a total of 4 inches upwards. I think I'm supposed to measure in inches but I'm not sure so I need help there. (h) And gravity which is 9.8 m/s^2. (g) The equation I'm using is V=[(mb+mp)*√(2*g*h)] /mb which I got from wiki on the ballistic pendulum and in the book 'Back Yard Ballistics'. 3. Now with the numbers plugged in I get: V=[(0.17+1.8)*√(2*9.8*4)] /0.17 which comes out to be 102.6 m/s which is about 229 mph. I think this doesn't seem right, so I thought maybe the height (h) is suppose to be in feet? So if I divide h by 12 I get 0.34. If I plug this into the same equation with same other variables it comes out to be 29.61 m/s which seems about right which is about 66 mph. For the force of impact, I could use E=1/2 mv^2 but that would give the result in joules which confuses me. If I want to find the force of impact, wouldn't I want to find the force in newtons? So to wrap things up, I need help in finding the velocity of a potato fired from an air powered potato cannon using a ballistic pendulum and I also need to find the amount of force the potato is exerting on the target upon impact. As you can probably tell from reading all of this, I am not great at physics but would love to be able to understand it so any help and correction is appreciated. Thanks!