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Unformatted text preview: Physics 2101, First Exam, Fall 2006 September 5, 2006 SSN : _____________________________________________ __ Signature : _______________________________________ __ Section: (Circle one) 1 (Ahmad, MWF 7:40am) 4 (Lehner, TTh 9:10am)
2 (Rupnik, MWF 9:40am) 5 (Ahmad, TTh 12:10pm) 3 (Rupnik, MWF 2:40pm) 6 (Ahmad, TTh 6:10pm) 0 Please be sure to write your name and circle your section above. 0 For the problems, you must show all your work. Let us know what you were
thinking when you solved the problem! Lonely right answers will not receive
full credit, lonely wrong answers will receive no credit. 0 For the questions, no work needs to be shown (there is no partial credit), 0 Please carry units through your calculations when needed, lack of units will
result in a loss of points. 0 You may use scientiﬁc or graphing calculators, but you must derive your
answer and explain your work. 0 Feel free to detach, use and keep the formula sheet. No other reference
material is allowed during the exam. 0 GOOD LUCK! Question 1 — 5 points The ﬁgure shows the velocity of a particle moving along the x—axis. Point 1 is at
the highest point in the curve; point 4 is at the lowest point. (a) (lpts) What is the direction of motion at t=O? towards positive x towards negative x the particle is at rest (b) (2 pts) At which of the four numbered points does the particle reverse its
direction of travel? ((2) (2 pts) At which of the four numbered points is the magnitude of the accel
eration largest? Problem 1  11 points A hot air balloon is ascending at the rate of lOm/s and is 80 m above the ground
when a package, which is at rest with respect to the moving balloon, is dropped
from it. (a) (3 pts) Sketch the acceleration, position, and velocity of the package as a
function of time after it has been dropped from the balloon, setting t=0
at the time the package is dropped. Use the axes plotted below for your sketches. m . ,_ . lOEé
47653.: E; t + 5 l : ‘113 @0791 _‘, L0 (not) \ 60 : 65JO M
 n48 ’C"+®f:*+3°‘“ (c) (4 pts) How much higher than the package are the people in the balloon,
when the package reaches maximum height? Question 2 — 6 points In the ﬁgure, the box is stationary and the angle 0 between the vertical and force
F is decreased somewhat. What happens to the following quantities during this change? Circle the correct answer. I 0 (a) (2 pts) The horizontal component of the force, Fm . 7
increases 0‘ ecreases remains the same (b) (2 pts) The static friction, f3 increases decreases remains the same (c) (2 pts) The normal force F
1 N I \
increase
® decreases remain th
s e same Problem 2  11 points A stone is projected at a cliff of height h with an initial speed v0 = 42.0m/s, directed
at an angle 60 = 60° above the horizontal, as shown in the ﬁgure. The stone strikes at A, 5.50 s after launching. NaletroCOSU’: 47—}; 2H2 (a) (3 pts) What is the height h of the cliff? I as 3‘ +5 mad“ ,1“ {A 3 .— Mo’ho“ ‘* x 1,3,...“ N / _ 4,3.“ (g9); zgqugsr
_ f. ,4“. 5; , + ‘ x y: “ 03¢), 18;» 4—39 3.. :9 i ,9 3 P 5
mpg 2t Eur.4: ye), ,q.?§+‘+ 364 Ext 1 ﬁgs) : 61. 3’6 u! (b) (4 pts) What is the speed of the stone just before impact at A? SQLed—a WM: gang} (U): ZW/S VJ: ~35? (SICs» 34.4 a: (c) (4 pts) How long after launching does the stone reaches the maximum height
H above the ground? Question 3 — 6 points The suspended body in the ﬁgure has a mass M , and a weight equal to M g. A
person is applying a force to the other end of the cord. Is the magnitude of the
tension T equal to, greater than, or less than Mg when the mass M is moving upward... ~—
r“
f
(a) (3 pts) at a constant speed?
T > Mg T < M 9 (b) (3 pts) at decreasing speed? T=Mg T>Mg Problem 3 — 11 points In the ﬁgure, a block of mass m1 on a frictionless plane inclined atlangle 0 to the
horizontal is connected to a box of mass mg. The pulley is massless and frictionless.
An upward force of magnitude F = acts on the box m2, which has a downward acceleration of magnitude (1 = ¢'1’. (a) (4 pts) In the space below draw free—body diagrams for .
box m2. (b) (3 pts) Calculate the magnitude of tension, T, in the connecting cord, express
ing your aHSWer in terms of mg, a, F, g, and numerical constants, as necessary. (0) (4 pts) Calculate the angle 0, expressing your answer in terms of m1, m2 , a, F, g, and numerical constants, as necessary. I L~ @640le —3 ML "" F ‘WB‘:
93 5‘ (m, ...
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