17. Periodic Motion
Spring Force (Hooke's Law)
1PRACTICE PROBLEM
A regular round bar has a mass M and a length L. A point mass is placed at a point parallel to the bar's length (on its axis), an arbitrary distance d from the nearest end of the bar. Using the relationship between force and energy (F = -dU/dr) determine the magnitude and direction of the gravitational force due to the bar on the point mass. For d >> L, prove that your answer agrees with the expected result.
![](https://lightcat-files.s3.amazonaws.com/problem_images/8e9ce6e32c49e6cd-rod.png)
A regular round bar has a mass M and a length L. A point mass is placed at a point parallel to the bar's length (on its axis), an arbitrary distance d from the nearest end of the bar. Using the relationship between force and energy (F = -dU/dr) determine the magnitude and direction of the gravitational force due to the bar on the point mass. For d >> L, prove that your answer agrees with the expected result.