 #1
 41
 4
Homework Statement
Problem: 4.93[/B]
The pulley is assumed massless and frictionless. The mass of the object attached to the pulley is given in terms of m, the force applied to the pulley is F (refer to diagram), and frictional force is f.
Question: Find the acceleration of the mass m in terms of F if there is no friction between the surface and m. Repeat if the frictional force on m is f.
Answer key:
aceleration=F/2m. (without friction)
acceleration=(F/2m)(f/m) (with friction)
Diagram:
Homework Equations
F=ma (Newton's Second Law)
Fnet (horizontal)= f+F (Calculating net force)
The Attempt at a Solution
My initial answer was similar to the key, except that I forget that the tension of the string attached to the mass is half of the force F. I get that the tension is less than the force F because there are two separate strings doing the entire force F, but I don't know why each is exactly half of F; it seems simple but I could not understand its behavior physically. My question: how do we know T= F/2? Why wouldn’t the tension of the side attached to the wall be greater than the tension attached to the mass, because the mass is probably less heavy and is movable?
Thank you!
Attachments

85.2 KB Views: 146