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Midterm

PHY 131 Study Guide - Midterm Guide: Mississippi Highway 1, Arc Welding, Microwave OvenExamPremium

12 pages82 viewsFall 2018

Department
Physics
Course Code
PHY 131
Professor
All
Study Guide
Midterm

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PHY131 Midterm 2 — Extra, Exam XXXXXXXXX (form: 1) 1
PHY131 Spring 2017, Midterm 2
Extra, Exam
XXXXXXXXX
Academic Integrity Statement
Please sign on side two of the answer sheet (over ”General Purpose Answer Sheet”). Your signature
acknowledges that your work on this exam has been done in accordance with an expectation of
academic honesty.
Fine Print
This is a closed book exam. You may use one sheet of notes - 81
2×11 inches, double sided, handwritten. ANY
manipulation of electronic equipment (iPod, iWatch, phone, laptop computer, taser, arc welder, microwave oven,
etc.) other than your calculator is strictly prohibited, and will result in a zero on this exam.
Your name and student identification number are printed on this exam. Before you start, enter your name and
student number on the answer sheet. Mark 1 in the “Test Version” box. Answer all problems on the bubble scan
sheet. If you think there is more than one correct answer for a given question, bubble in all of the correct answers.
Some potentially useful expressions and constants are:
proton mass 1.67 ×1027 kg neutron mass 1.67 ×1027 kg
electron mass 9.11 ×1031 kg electron charge 1.6×1019 C
speed of light 3.0×108m·s1gravity acceleration 9.8 m·s2
derivative of a power d
dx (xn) = nxn1integral of a power Rxndx =1
n+1 xn+1
Each question carries equal weight. Answer each problem with the answer closest to the correct answer. When
mistakes are found, the problematic question will be excluded from the score.
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PHY131 Midterm 2 — Extra, Exam XXXXXXXXX (form: 1) 2
1. An mb= 19 g bullet traveling vi= 3.5×102m·s1penetrates an mB= 2.0 kg block of wood
sitting on a frictionless table and emerges going vf= 1.6×102m·s1(this is an inelastic collision).
If the block is stationary when the bullet hits, how fast is it traveling as the bullet exits?
A. 1.8 m·s1
B. 1.8×103m·s1
C. 0.017 m·s1
D. 19 m·s1
E. 58 m·s1
SOLUTION: Momentum is conserved, so Pi=Pfand we can write that
mbvi=mbvf+mBvv=mb
mB
(vivf)(1)
v=(19 g)(0.001 kg·g1)
(2.0 kg) (3.5×102m·s1)(1.6×102m·s1)= 1.8 m·s1(2)
2. A ball with mass m= 1.83 kg, radius r= 0.100 m and moment of inertia I= 0.00800 kg·m2is
initially at rest and rolls without slipping down a ramp sloping at 25.0to the horizontal. What is
the magnitude of the acceleration?
A. 5.18 m·s2
B. 7.58 m·s2
C. 2.88 m·s2
D. 4.14 m·s2
E. 9.47 m·s2
SOLUTION: The motion of the ball is described by
ma =X~
F(3)
Iα =X~τ (4)
and since the ball is rolling without slipping, α=ar/r, with a torque of τ=rFrwhere
arand Frare parallel to the ramp. Therefore
mar=mg sin θFr(5)
Iar
r=rFr(6)
Solving for the acceleration gives
ar=mgr2sin θ
mr2+I=(1.83 kg)(9.8 m·s2)(0.100 m)2(sin 25.0)
((1.83 kg)(0.100 m)2+ (0.00800 kg·m2)) = 2.88 m·s2(7)
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PHY131 Midterm 2 — Extra, Exam XXXXXXXXX (form: 1) 3
3. Given ~
A= (0.56,0.56,2.8) and ~
B= (5.0,3.9,1.7). What is the dot product of ~
Aand ~
B?
A. 2.9
B. 7.2
C. 9.7
D. (10,13,0.62)
E. (0.62,2.6,2.0)
SOLUTION: The dot product is
~
A~
B=AxBx+AyBy+AzBz= (0.56)(5.0) + (0.56)(3.9) + (2.8)(1.7) = 9.7(8)
4. Given ~
A= (3.9,5.0,0.56) and ~
B= (5.0,0.56,2.8). What is the cross product, ~
A×~
B?
A. 21
B. 8.6
C. (14,14,23)
D. (17,4.4,21)
E. 23
SOLUTION: The cross product is
[(5.0)(2.8)(0.56)(0.56)]ˆ
i+[(0.56)(5.0)(3.9)(2.8)]ˆ
j+[(3.9)(0.56)(5.0)(5.0)]ˆ
k
(9)
(14,14,23) (10)
5. A crate is on a ramp tilted at θ= 40.2to the horizontal, with µk= 0.100. What is the
acceleration of the crate?
A. 6.85 m·s2
B. 6.64 m·s2
C. 7.07 m·s2
D. 5.58 m·s2
E. 6.33 m·s2
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