PHYS 2101 Midterm: PHYS 2101 LSU 2010s 2
Physics 2101, Exam #2, Spring 2010
March 3 , 2010
Name:___________________________
ID#:____________________________
Section: (Circle one)
1 (Rupnik, MWF 8:40 AM) 5 (Jin, TTh 12:10)
2 (Rupnik, MWF 10:40 AM) 6 (González, TTh 4:40)
3 (Zhang, MWF 12:40 PM) 7(Sprunger, TTh 1:40)
4 (Plummer, TTh 9:10)
• Please be sure to write (print) your name and circle your section above.
• Please turn OFF your cell phone and MP3 player!
• Feel free to detach, use, and keep the formula sheet. No other reference material is allowed during the
exam.
• You may use either a scientific or a graphing calculator.
• Show all your work for the problems that are not multiple choice!
• There are a total of 10 problems (total points add to 100 pts)
• GOOD LUCK!
!
1. (Show all of your work) The figure at the right
shows a potential energy diagram U as a function of
x for an object of mass 1 kg.
(A) (5pts) At the point x =3m the object has a
velocity of 2 m/sec. Find the mechanical energy
Emech for this system and draw a line on the
figure to represent the mechanical energy.
(B) (5pts) What is the allowed range of the motion along x given the mechanical energy found above
(hint: you can read this off of the graph)?
(C) (10 pts) What is the force (magnitude and direction) acting on the object in each regions of the
potential energy diagram in the allowed range of motion? Your answers should first describe the
region (x values) and then the magnitude and direction of the force.
!
Document Summary
7(sprunger, tth 1:40: please be sure to write (print) your name and circle your section above, please turn off your cell phone and mp3 player, feel free to detach, use, and keep the formula sheet. Your answers should first describe the region (x values) and then the magnitude and direction of the force: (5pts) a massless spring of spring constant k= 25. 0 n/m hangs motionless from the ceiling. You carefully attach a mass to the end of the spring with a weight of 5 n without letting the spring stretch and then let go of the mass from rest. The spring stretches out a distance d until it momentarily comes to rest. The two particles undergo a one- dimensional collision. The track is frictionless except for the horizontal region from x=0 to x=l. Completely inelastic: (show your work) (30pts, 5 pts for each question). A bullet of mass m and velocity v0 is moving in the positive x direction.
