# Thread: Projectile Motion

1. ## Projectile Motion

I need help for physics homework. Here is what is given. m=10 g c=.5 (drag coefficient) r=.125m we are given information on a "test run" which is launched at an angle of 66 degrees and has a max height of 1.68 m above the launch heigh, which is unknown. We need to derivate a formula that will able us to find inital velocity. Then we need to check the formula with our test run to make sure it will work. Tomorrow in class we will be given the angle and height, and need to be able to plug into the formula to guess where the ball will fall, and then we place a bucket there, if we get the ball in the bucket, we pass, if not we fail! HELP!!

2. Originally Posted by hayn7786
I need help for physics homework. Here is what is given. m=10 g c=.5 (drag coefficient) r=.125m we are given information on a "test run" which is launched at an angle of 66 degrees and has a max height of 1.68 m above the launch heigh, which is unknown. We need to derivate a formula that will able us to find inital velocity. Then we need to check the formula with our test run to make sure it will work. Tomorrow in class we will be given the angle and height, and need to be able to plug into the formula to guess where the ball will fall, and then we place a bucket there, if we get the ball in the bucket, we pass, if not we fail! HELP!!
You're given a drag coefficient so obviously you can't neglect air resistance. Have you been told what form to assume for the force due to air resistance? If it's proportional to the speed of the projectile, then the problem can be solved exactly and formulae derived for all sorts of things. If not, then the problem must be modelled numerically.

You give a value of r ...... What's r meant to represent (some quantity with dimension of length, I assume)?