Calculating Force of 25 lb Bag Hitting Object

  • Context: Undergrad 
  • Thread starter Thread starter kgtp1999
  • Start date Start date
  • Tags Tags
    Force
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
2 replies · 3K views
kgtp1999
Messages
2
Reaction score
0
Initially, a 25 lb. bag is hanging straight down from a 7 ft rope at the center of an object next to a vertical wall. The 25 lbs is raised until it is about 45 degrees or 5 ft from the object and then released. How do I determine the force that hits the object? I am only looking for a simple approximation without the weight of the rope or wind.

Thank you for your help!
 
Physics news on Phys.org
When you release the pendulum it converts gravitational potential energy (GPE) of the raised weight at 45 degrees, to kinetic energy (KE) of impact. You can easily find GPE and KE but if I recall properly the force during collision depends on the elastic properties of the bodies. Also it is not clear what the "object" is in your problem statement.

Edit: hyperphysics treats the basic concept of impulse force here:

http://hyperphysics.phy-astr.gsu.edu/HBASE/Impulse.html

The formula Favg*d = -(1/2)m*v^2 appears at the link page and might solve your problem if stopping distance "d" can be estimated as the bag comes to a stop as it hits the object.
 
Last edited:
The object is a plastic prototype secured to the wall. When the bag hits it the object has no substantial elasticity. So given the stopping distance is 0, would it be just a matter of finding the velocity as the weight is about to hit the object?