posted by Mack on .
A 500g ball is dropped into a well that is 10m deep. A)What is the ball's potential energy before it is dropped? Take the bottom of the well to be at zero height. I solved by using PE=mgh and came up with 49J. B) What are the kinetic energy and potential energy when it has fallen 7m? How fast is it traveling at this point? I used PE=mgh but used 3m for h and came up with 14.70J. Then solved KE=1/2MV^2 and used 7m for h and came up with 34.28J. I know these two have to equal the starting PE due to law of conservation of energy which they come pretty close. Did I do this right or did I use the wrong numbers in h?..Then for the last part I used V=sqrt2gh and came up with 11.71 m/s. I appreciate any assistance or pointers on this.