# Physics 253 – Basic Mechanics Fall 2014 Problem Set #9

```NORTHERN ILLINOIS UNIVERSITY
PHYSICS DEPARTMENT
Physics 253 – Basic Mechanics
Fall 2014
Problem Set #9
Problem Set Due: Wed., Nov. 5, 2014
Read Lecture Notes #11 (Giancoli: Chapter 9)
There will be a Quiz #3 on Friday, Nov. 7, 2014
Remember to write all answers with the proper # of significant figures
Show explicitly all your work for full credit.
1.
2.
3.
4.
5.
Giancoli: Problem 12
Giancoli: Problem 34
Giancoli: Problem 50
Giancoli: Problem 56
Giancoli: Problem 62
page 241
page 242
page 243
page 243
page 244
which direction?
which direction?
6. Two blocks collide elastically on a frictionless surface.
(a)
Write down the conservation of momentum relation for this problem.
(b)
Write down the conservation of energy for this problem.
(c)
Solve the set of simultaneous equations above for the final velocities of the blocks
after the collision given v1i  2.0 m/sec, v2i  2.0 m/sec, m1  0.50 kg, and m2  0.30
kg? (zero credit for just using canned formulas given in Giancoli—I expect to see your
own algebra). (1.0, 3.0)
7. Three blocks each of mass m are located on a frictionless track as shown above.
After block A is released it makes an inelastic collision with block B (they both
stick together) and the two of them in turn collide with and stick to block C .
(a) Find the final velocity of the three blocks as they move off together in terms of g
and h . (solution:
2
3
gh / 2 )
(b) Find the total energy converted to heat in this entire process in terms of m , g ,
and h . (solution: 13 mgh )
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